If you have enough ENERGY, minimum 60ft/#'s, then I think you can consider a Mech. BH. BUT, I think you should still tune to shoot Fixed BH's well, because it will optimize your bows tune to you're specific shooting form. It's not nearly as much about SPEED as it is about energy with many set-ups. If you get 280fps out of a 255gr arrow, you have absolutely no business putting a Rage 2 or 3 blade on the tip of that arrow. You may even find some TARGET archers putting BH's on arrows to FINE TUNE their target bows, because they accentuate any tuning issues and allows for that ultimate fine tune.

"I like to get my KE from a light arrow and lots of speed"

Statements like this show how mislead some are by thinking they're optimizing KE with SPEED. There's a point with most set-ups where you will find an optimal KE, and it's not gonna be with an IBO arrow, that is for sure.