We've got some veteran mod authors from other modding communities that I recognise here and we've also got some budding new comers who might not have ever done any modding before, so I'd love to share my thoughts every once in a while to see how things are going, how things are progressing and what, if anything, I can do to help. Just so you know, my name is Robin and I run Nexus Mods. I've been a part of the modding community for going on 12 years now and while I've always been crap at "arty farty" stuff (what I call graphics, texturing, animations and scripting), I've always tried to help where best I can, and that's where Nexus Mods came from.
Today I wanted to write a "quick" post about the reasons and merits of using multiple different file hosts to share your great mods with others, because right now there's a big skew towards Steam Workshop due to the easy integration with the editor and the beta access currently being Steam exclusive. I've already spoken to some of the mod authors here via Steam chat, but I wanted to get a post up about it so I can see what others have to say on the matter

So where should I upload my mods and dungeons to? Steam Workshop or Nexus?
The short answer is BOTH.
Steam Workshop is great because it's simple for both mod authors to upload their mods and mod users to download the mods while opening up modding to a wide install base. It's hard to go wrong with Steam Workshop and it's very mod user oriented. Unfortunately it has a massive down-side in that only people who bought the game on Steam can download and play the mods on Steam Workshop.
On the flip-side, Nexus Mods has always been about mixing the simplicity of uploading and downloading mods with the option to go wider and deeper with more tools and choices for those who want to get a bit more complex, and making it available to everyone. You can easily keep things very simple, much like Steam Workshop, or you can make use of the more extensive tools on offer. It's your choice. We don't want to treat all modders like simpletons, because we know lots of you like to do lots of different stuff with your mods. That's what modding is all about, after all. That's why, for example, we give you the option to download and install the mod through our client, the Nexus Mod Manager, or manually which provides you with the raw archive of files to do with as you please.
As far as I'm concerned mod authors are the most important part of the modding community. Without them, there is no community. That's why we've always focused the Nexus sites around making them as user friendly for mod authors first above all else. If you keep them happy, then everything else will fall in to place much easier.
A case study
From the Skyrim modding community where there's both a Skyrim Nexus and a Skyrim Workshop it's become relatively apparent how the traffic has moved within the community. Many many players and modders were already aware of the Elder Scrolls modding scene before Skyrim from Oblivion and Morrowind. Many were already aware of the Nexus where the majority of the mods on offer were available. When Skyrim Workshop came along, rather than splitting the community, it provided a new avenue of potential modders and mod players in to the community. So rather than some traffic getting redirected from the Nexus to the Workshop, the Workshop actually complimented the community by introducing modding to those originally either unaware of it, or too afraid to go to a third-party site to understand and get their mods.
As time went on, many new users who had been introduced to modding through Steam Workshop were either becoming more open to using the Nexus, or using it freely, either because they'd learnt that modding wasn't satan incarnate that was going to eat their computer whole, mods were only on the Nexus or because they couldn't be uploaded to Steam due to the 100mb file size limit, or the requirement of third part tools like Skyrim Script Extender (SKSE), which Steam Workshop doesn't support.
In essence, Skyrim Workshop became the place where people new to modding went to cut their teeth on modding before moving on to the Nexus. The two compliment each other well.
In Grimrock, things are slightly different as it's the first in the line of this game. There's no modding community that can move from an old game to this new one, so what we have here, on this official forum is the foundation of an entirely new modding community. However the Workshop and Nexus can still compliment each other well. Steam brings with it it's huge install base and community, and Nexus brings with it it's large community as well as its seasoned and veteran mod authors. It should never be about an "us or them" exclusive scenario where people only use one or the other, it should be about "us and them", making use of the merits and advantages of both to ensure this community is as open and popular as possible.
Distributor issues
One of the biggest reasons you should be uploading to both, however, is that many people who don't have the Steam version of Legend of Grimrock will not be able to play your mods if you only upload them to Steam Workshop. Steam Workshop is Steam exclusive, meaning that only people who have the game on Steam can download from it. Nexus Mods is distributor agnostic, which means that no matter where you bought your game from (including Steam) the mods on the site will always work. So if you only upload to Steam Workshop then you limit the amount of people who can download and play your mods. By uploading to both sites you are able to catch the entire Legend of Grimrock player base, rather than only a part of it.
At the time of writing the editor is currently in beta and only Steam users can currently play mods and use the editor. When the editor is out of beta and the game and mods are available to all players things will be very different. There are a lot more dungeons currently available on Steam Workshop than on Nexus Mods, however, like-for-like traffic on the mods available on both sites is extremely similar. Nexus Mods is a large network with a large following. You might think that Steam would have more traffic, but it hasn't been the case with Skyrim, and if you give it a chance, it probably won't be the case with Legends of Grimrock either.
At the end of the day it's all about choice. Choice for you, and choice for the users of your mods. Not everyone likes Steam, and not everyone likes the Nexus. So giving people the choice to use both platforms is great for everyone. I imagine that's one of the main reasons Almost Human liked the idea of working with both Steam and Nexus Mods. End-user choice

Extra management time?
It's true that by uploading to more than one site you are increasing the time it takes you, the mod author, to manage your mods. It means you've got to upload your mods to more than one site, and manage the pages accordingly. Personally, I don't think it should take you that much time, especially with how small the file sizes are with Grimrock dungeons right now and how easy both sites are to update your work on. We're talking a matter of minutes here and hey, by uploading to both sites you avoid those annoying comments on your mods asking you if you can upload it to the other site

I completely understand if you only want to use one site or the other. But I wanted to get a thread out there about the merits of using both sites and would love to hear your feedback on the matter.