Again, thanks for the input, guys. I'm going to have to get some single bevels, in addition to upping my arrow weight.
One thing I wonder about. I fletch my arrows with wild turkey feathers, and I use both left and right wing. I've never seen a bit of difference in how they fly, but I have to admit I'm not crazy about having to buy (and keep track of) left and right beveled heads. I could just fletch all my hunting arrows left and save the right wings for targets and bunnies. But what I really like to do is make all my arrows the same, and put broadheads on the best-flying ones right before hunting season.
That's about the only advantage I'm seeing for double bevel. That, and I already have some. ha ha