What is CZ doing? Getting rid of a stock of CZ75 slide release levers. The same spring that holds the left side slide release lever in place also holds the right side lever. There's a bigger hole in the right side of the frame to accommodate the right side lever/sleeve that fits over the left side slide release shaft.
Getting the right side lever out is easy once you've removed the left side lever to get the slide assembly off. You just rotate it around and pull and the spring rides up out of the slot in the sleeve and it pulls out. But, getting it back in again is the big PITB. You have to get something to force the spring upwards out of the path of the right side lever till you get it in the frame. Not impossible or even super difficult, just different than pushing the left side back into the frame.
And, the race hammer from either CGW or CZ Custom will get rid of the annoying ledge you speak of. It may not shrink the groups, but it'll feel a lot better.
A year or so back Joe was talking about the triggers on his pistols he shoots competitions with. He said something about liking a hammer/trigger with some drag/creep in it vs. a clean crisp trigger. I thought he was crazy at the time. I really like a nice clean crisp trigger and always believed it helped you shoot better. But an experience with that M&P 2.0 showed me I didn't shoot any smaller groups with an awesome trigger (Apex trigger and kit) than I did with the ugly butt factory trigger with it's flexing and draggy/creepy/nasty feel/pull. Sort of reset my brain on triggers.