Don't worry about bending backstraps with a 44 or any other caliber, particularly Cap & Ball... Ruger had Brass gripframes on Super Blackhawks, and you can still buy them aftermarket. I have several brass gripframed revolvers with no problems, and if the recoil were capable of bending a backstrap, it would break your hand first.
A brass receiver frame is another story, and even a 36 will wear out faster, as the steel cylinder beats the recoil shield back and opens up the cylinder gap, and the cylinder pin (on a Colt) is threaded into the brass. A steel receiver will last a lot longer, as someone mentioned, loading is as stressfull as shooting a Colt open top.