RE: Bear Montana
Some people don't loose much or anything, but I would say that would be the exception. A lot will depend on the differences of anchor, stance, and release aid. The only way to really tell would be to measure. I know for me personally, I gain a full two inches going to compound.
Keep in mind that 45#s will and has taken downmany deer with the right arrow and tip and shot placement and is fully capable for hunting deer.