I voted N/A, but only because I wanted to see how the Yes/No vote was coming along without biasing the vote. It's not like I thought the idea itself was not applicable, but this is the kind of thing that I think we ought to let our members decide.
I really like the idea and although I'm not a musician myself, I don't think that such a forum would be any less alienating than the DIY forum is to someone like myself (who is a decidedly non-DIY type), or that the High End forum may be to others (although, I must fess up about being pro-High End).
First, let me share some general thoughts about our DIY forum, because I think much can be learned from the way that it operates. In fact, it may serve as an excellent example for the Musician's Forum to follow, if such a forum were to become a reality.
As much as I'm not "naturally" interested in most DIY topics (and couldn't see myself doing much, if any, of it myself), I do from time to time find some DIY threads to be quite intriguing. It's also fun to be a "fly on the wall" at times, and enjoy reading the back and forth among those who are more intimately familiar with the topics under discussion. More to the point, we need the DIY forum to help advance/promote the state of the art within our hobby. To have DIY threads mixed in with the regular headphone, amp, source and cables forums would both distract from those forums and dilute the efforts of those who are most interested in building the DIY community.
But still, as much as the Head-Fi community needs the DIY forum for all sorts of good reasons, there may be some people who feel "alienated" by it's presence because it's so technical and scary and so on. Silly, when you think about it, because the more you learn about such things, the less technical and scary they will seem. It should only be scary if you decide to start posting in a highly technical thread, the subject matter of which you have no understanding of! Unfortunately, some people have no such fear, but I digress.
What I think the DIY forum (and by extension the various active "DIY type" Head-Fi members) has accomplished over the years is twofold:
1) it/they have helped, in no small measure in the early years especially, to advance the state of the art within the hobby, mostly with respect to amps and cables, but in other productive ways as well, but
2) it/they have done this without intentionally alienating the non-DIY types, to such an extent that the non-technical "everyday" folks at Head-Fi who have zero background in electrical engineering (or whatever) can still ask simple, even naive questions within the DIY forum and get well reasoned and respectful answers. It has always been a shared passion and not an "us" (technical types) versus "them" (idiots like me), although I suppose they may smirk from time to time, and that's Ok with me; I know some things that they don't know, and so does everyone else who posts here.
In other words, the DIY crowd has it's playground and they can do what they want to within "their" forum. At times (see point 1 above) they may need to more or less communicate between and among themselves on the more "serious" technical topics, in order to be productive. Yet, at other times, and I think most of the time, they have a more embracing attitude (see point 2 above) in the sense that they encourage non-DIY types to ask the simple/basic questions, and in fact, to give DIY projects a try for themselves. There were even "group build" types of threads years ago, where everyone started from the same kit and worked through an amp building project step by step with all sorts of expert support within the thread and via PM.
So what's my point in all of this? Well, if it isn't obvious by now, I think that if we are to have a Musician's Forum, it really shouldn't be designed with exclusivity in mind. Instead, it should be a place where our resident Head-Fi musicians, of whatever instrument and whatever skill/experience level, can gather and talk shop about things that they find most interesting about being a musician, but with the understanding that you don't just wake up one day and play like Eric Clapton. It's a process of becoming more so than a state of being, so no need for the snobs to apply. Or at least that's my take on it.
Some of the threads will naturally be more inviting for non-musicians to participate in than others, but that's the nature of the game. If you don't know how to play a guitar, or to write music, or even to read music, but want to learn, I suspect there will be people who can give you all sorts of pointers. In theory, we could do all of these same sorts of things in the member's lounge, but I think our community is much stronger due to the contributions over the years from the DIY folks in terms of what they've been able to do with "their" forum. I'd hope that the same could be said with respect to musicmanship in a couple of years if the Musician's Forum becomes a reality.