I'll pick too light over too heavy any day. 45# is plenty to take a whitetail, and may be really appreciated after a few hours on a cold stand when the shot presents itself. You might be able to handle the 50# with no problems, and you will probably build up pretty quick, but.........

When I swapped, I was shooting a 70 or 80 # compound (forget which). My first trad bow (recurve) was 55@28, I probably pulled it between 29 and 31" (didn't have a clue what I was doing). Next bow (longbow) I was pulling 80#--way too much. Had to overcome a lot of bad habits because of it--some I still fall back into.

Hard call to make, but the safe bet, in my opinion, is the 45#.

Chad