Many studies have repeatedly shown that final knee motion after replacement depends on preoperative motion. It's also true that patients with the greatest loss of motion have better results than patients with minimal loss of motion.
Recently a group of researchers in England and Canada got together to review the results of total knee replacements. They were especially interested to see what factors predict final motion measurements.
They found that age, gender, and body weight didn't seem to make much difference. Likewise the type of implant was no longer such a big factor. The amount of knee flexion before replacement was still pretty important.
It's likely you'll notice some difference with the new implant. Let us know how you compare them!