As long as the rants and raves are limited to ideas, actions, and frustrations, I think the forum might be interesting. However I am afraid it might also provide room for some personal attacks and we have more than enough of that on Curezone now. Will the forum be tightly controlled enough to prevent a rant about "I Hate Every Word Hopinso Utters", or "Mr. Cooties Is A__________" (fill in the blank, I happen to enjoy your posts)? A place to vent is wonderful, a place to attack, or even rant against political stands or religious convictions will just cause negativity, and we already have to endure too much of that.
All that said, I think if the forum will be patrolled closely and personal attacks will not be tolerated, then its a good idea.