I have an RMR CC, but honestly have not done more than just play with it. For the way I use small guns, an RDS just gets in the way, so all my dot guns are "normal size", with normal size rds. I currently only use RMR's or Acro's for carry.
As far as needing practice, that really isn't the issue in my mind. First, everyone needs more practice, but finding the dot on presentation is the easy part. Its finding the dot again and again when doing things like one handed shooting under a car at a weird angle. Doesn't matter how good a shooter you are, a bigger window helps with all the non-square range stuff guns are meant for.
RDS are awesome on pistols, but they have some serious drawbacks for the vast majority of even skilled shooters. An RMR is marginal in window size, but totally useable with a lot of practice. The Acro is a drop easier. Who knows what will come down the road to improve our use of them.
The CC certainly looks good when direct milled to a 1911. I will have to play with it some more, but I don't mind a little overhang.