Bob, IMO 45 pounds is sufficient hunting weight, especially for whitetails. If you find that 45 pounds is more enjoyable to shoot than the heavier weights you have previously shot, then I suspect you will most likely shoot more often, therefore making yourself a much better shot due to the increased practice.
Remember, if you hit a whitetail in the ribcage area where you should, you will have no problem getting a clean passthrough with 45 pounds.
I use to shoot 70 pounds, until I learned how to tune my bow properly with the right spine arrow. With the correct spine arrow, your shot will be much more efficient, easily allowing you clean passthroughs.
I now shoot around 52 pounds, and will never consider going back to pulling over 60 pounds as it is the point of diminishing returns in bow efficiency.
If I were hunting Elk I might consider using a heavier bow, but still not over around 60 pounds. Instead, if I were concerned with penetration, I would choose a heavier arrow in the correct spine. Cedar arrows are the lightest available, but you can get up in the 900 grain range when shooting hardwoods like Hickory. With the heavier arrows penetration is no problem whatsoever with a properly tuned arrow, even on the largest of North American game. Also, there are several different arrow materials that will give you weights between the Cedars and Hickorys. Douglas Fir, Poplar, Birch, and Ash just to name a few.
Carbon and aluminum arrows can be internally weighted as well for increased penetration, but it's usually not necessary for medium sized game.
Remember, most states will legally allow you to hunt with 35-45 pound bows, so they are definitely adequate in getting the job done with proper shot placement. Also keep in mind that most all of the top olympic tournament shooters shoot recurves in the 45 pound range and there is a reason for that. They are much more accurate with them than with heavier bow weights
