Most of what makes the CW45 cheaper you're thinking about replacing?
If you're thinking about doing those things, just save up the extra $200 and get the P45.
The only reason being is that with the P45 you have the dovetailed front sight, not the staked on front sight. Dovetails are better, and you'd have to pay more to have the slide cut for it. There also seem to be more options for a night sight to fit the dovetail.