In case this is my first reply that you're reading, I'm just your fellow Photosynth user - not anyone from Microsoft.
No, it really isn't feasible to read every comment and yes there ought to be a way here on the forum to search the forum.
That said, there isn't and there hasn't been since the site got its own forum in early 2009. (Before that we all used Get Satisfaction over at http://getsatisfaction.com/livelabs/products/livelabs_photosynth which does have built in search.)
(And yes, we've been asking for this feature from the beginning of this forum.)
Here are some tips for finding discussions on a topic:
1) When you've drilled into a forum (Suggestions, Bugs, Advice, etc.) you can use your web browser's page search [Ctrl]+[F] to find a term on that topic list.
2) You could search Get Satisfaction or Photosynth's official blog at http://blogs.msdn.com/photosynth .