I bought the S type screen for my 7D, and was the first to get the S type screen for my 5D3. both from focusingscreen.com. easy as pie to change them if you have the right precision screw driver from Craftsman. 2 screws, thats it. and it makes the WORLD of difference if you use fast primes.
i dont know about you, but using live view would be IMPOSSIBLE to do while maintaining any kind of speed of handling, stability, etc. dont get me wrong, if i'm on a tripod, and had a 6stop ND on a prime to shoot wide open with strobes, AND the subject is cooperative, then yeah live view is the only way to go. but for almost every other kind of shooting i do i find the high precision screen to be a tremendous aid.
and let me add, that actually seeing what the frame looks like at f1.4 is also a tremendous aid too. you know when you shoot something what it will look like, vs having to chimp. (if you often shoot f1.4-2.8)