Sitefinity for my project?

Before getting started, I'm trying to evaluate the feasibility of using Sitefinity as the foundation of an extremely specialized sort of community. Users will be posting forum-style and commenting on things. Probably also submitting projects, articles and documents. I see "CMS Users" are one of the distinguishing features of the license. Most licenses only allow 1 CMS User. What's the definition of CMS user? What can a "CMS User" do that a normal (registered) user cannot? We're looking at 50,000 registered users with probably 100 online at any one time, but we only need a few "admin" and website editor users.

How quickly could I build a simple forum system (like the Umbraco Forum, for example) on Sitefinity? How appropriate would this be?

*bump*

Hi Eric,

My personal opinion is that Sitefinity 4 isn't ready for use as a community platform. Why would you want to recreate something like the Umbraco Forums when Umbraco has them already? Since Forums are not currently available in SF4 and based on current roadmap won't be available in Q1 either (mid april) you'd be waiting a while. If you have the time, resources and budget to customize SF to make it into something that supports a "community" then go ahead but that just doesn't make any business sense to me. I might be missing something about Umbraco and admittedly and not familiar with it, maybe there's a show stopping feature or two over there and that's why you're looking to see if it's a better option to customize Sitefinity.

As for the "CMS User" part of your question, there have been a number of posts on this subject as it's a pretty big issue for a lot of users with the new licensing model. In SF 3.x there was no limit to the number of concurrent "Backend Users" (note, this is the term Telerik uses for users that can log into /sitefinity/ backend and edit content) however in SF 4, if you look at the breakdown there are limits and they're rather restrictive. However, your "community" users would not have to be members of the "backend" user role. This also means that they wouldn't be able to use any of the backend tools to add/edit content so you'd have to create your own set of tools for the front end that took care of any and all editing. Again, I think this proves that for a community site Sitefinity 4 just isn't ready yet. Now if you could talk them into giving you a license for SF 3.7 you'd be in business, as it has Forums (simple but they worked) and unlimited backend users. Realistically I wouldn't do this though as I think they're in a rush to phase it out as it's not a money maker for them.

Hope that helps you out a bit. Anyone can chime in if I've got something wrong here but I think I've described things correctly.

Cheers,
Phill

Excellent answer. Let me see if I get this right: the "backend" users are the only ones mentioned in the Sitefinity license. And the only thing they cannot do is work with the /sitefinity admin pages. But if a module were to provide public-facing content creation tools (blog comments, etc), those would be called "community" users and not subject to the license restrictions? Are there any things in the API that such users would be prevented from interacting with (assuming the presence of a UI to expose them)?

But, on the question of my custom "forum", let me reassert that it will be specialized and only forum-like. The reason we're considering a custom solution rather than trying to conform an already-produced forum/blog combination is that we've tried many combinations of platform before, and are just fed up with bugs and patch cycles. Our needs are unique enough that we feel that a custom solution would fit us better. I'm just trying to get a better idea of the expected cost (time+labor) that a RYO on top of Sitefinity would cost versus on Orchard or Umbraco.