RE: broad heads or mechanical?
I'd stay away from mechanicals, period. Besides the fact that anything with moving parts is more apt to have a problem (one of the reasons I swapped to trad bows), you loose energy with mechanicals, and most folks don't have it to spare with trad bows.
One reason compound shooters use mechanicals to get around tuning. With the high speeds and light arrows, being just a little off in tuning will show up more with fixed blades.
For what it's worth, I've never had a problem getting 2, 3, or 4 blade broadheads to fly great from a trad bow, even with my not-so-good release. I have never had to make any adjustments when swapping from field points to broadheads with my longbow.
Chad