First off, congratulations on how popular the board's become. Personally, I'm not surprised; it's a hell of a piece of work.
I can completely understand how a project of this scope could occupy more time than you have... Been there a few times myself. And though you didn't say it specifically, I bet it can be really frustrating to want to do a lot more to improve it than you feel you have the time for. To be honest, I've been really amazed at the amount of time you've dedicated to improving and supporting WWWThreads up to this point. You've got to be a prime candidate for Carpal Tunnel Syndrome by now.
Anyway, I wouldn't have a problem with you setting up support contracts. The only drawback that I can see to that approach is that, unless you enact a strict policy for yourself of not responding to requests for help on the "free" boards, you'll not only have the load you have now, but you'll also have another set of people who you'll then be obligated to make time for. If you aren't careful, you'll end up having to spend even more time supporting the board than you already do. Do you think you can do that? I'm not saying you can't -- but considering how helpful you've been to this point, I bet it'd take a huge effort for you to refrain from trying to help everyone with a problem. It sounds, though, like that may be what you need to do.
If that's the way it's got to be, so be it. You've set up a great infrastructure for users to help each other here, and there seem to be plenty of people who'd be willing and able to answer just about anything that pops up. I think one of the reasons that users aren't always answering each others' questions currently is that it seems like you'll always chime in with an answer eventually. If you can't be relied on to answer everything, though, I honestly believe the gap will be filled somehow. Maybe not right away -- it'll take a little while for people to get used to the fact that they haven't got near-instant 24-hour tech support from the program's author -- but it'll happen.
As far as going to a commercial version to keep the quality high... well, that's your choice, and I'm not about to tell you not to do it. I would, however, like to toss out a couple other options to consider, especially since you said yourself you're "shying away" from that:
Make it easier for others to contribute fixes and improvements to the code.
Right now, it can be a bit difficult to contribute changes to the code. We can never really know what parts you might be working on, so the code's something of a moving target. I believe I say a post by you a while back saying that you'd consider setting up the code on a CVS system, which I think would be great, and I believe would go a long way toward making it possible for others to do some of the work you're now doing.
Delegate
Right now, if I'm not mistaken, every change to the WWWThreads code has to be entered by you at some point. Users can post customizations on that board, but for them to be incorporated, you've got to personally add them to the code. When a user who may not be able to write code suggests a modification, in most cases you've got to figure out how to do it, then make the code changes.
How about if you had a board (or something similar) where you could post things like "Who will add the ability to have both Post and Preview buttons?" (just as an example, since a certain person who shall remain nameless seems to think it'd be a good thing []/forumimages/smile.gif[/]). Again, I think this is a situation where a revision control system would be of great benefit, to keep multiple coders from stomping on each others' toes (including yours) as they make changes to the various modules.
In any case, this being your project, you should have every right to say what should and shouldn't be added or modified in the code, but it seems to me you might free up a lot of time for yourself if you didn't have to be the guy who did everything. Of course, that might mean letting go of a little of the control you have now, so it's also a matter of how much you want WWWThreads to remain a solo project.
Apologies for not responding sooner -- and whatever you decide, thanks for letting us know what you're thinking. And thanks again for giving us this really great piece of software.
