One challenge I have had with the CZ 135 f/1.8 is close up shallow DOF shots. It is tough to get plane of focus where you want it. In the end I've found focusing far out and then pulling until the area I want in focus just comes in sharp. Stop there, no rocking and shoot. This is a tripod-only endeavour of course, cannot be done accurately hand held.
So I'll be buying the type M soon. At the cost of a little viewfinder brightness (no biggie with f/2.8 or faster lenses) the contrast for focusing should be a lot better.
There's a good video on how to install it as well:http://support.sony-europe.com/dime/tutorials/A900_foc_screen/FDA_FM1AM.aspx?site=odw_en_GB&m=DSLR-A900