I'm gonna have to back Joey on this all the way...
I have been to some of the WIG (Western Independent Grays) events. If you really want to see quality impressions, and talk with guy's, (and sometimes gal's portraying civilians) these are events to take note of.
History Heavy is correct, you may get a look at things in a camp setting you won't see at a mega-fest. You won't see numbers, but quality is the key. The WIG events I have been to, we were encouraged to talk to the spectators... answer questions.
Now, both groups that Joey mentions at times will have campaigner type units form up at the Mega Fests. Several events I have been to were on actual battle grounds that were contested for by the lives of both sides. Being able to go to an actual battle site, and talk to guys that really care about history, and go to the trouble to share that knowledge, may have you walking away with a better understanding of the WBTS soldier.
Kevin Dally