I have both a CZ-75B and a CZ-85B Combat. (I've had the CZ-75 for months, and got the CZ-85B Combat yesterday; shot it for the first time, today.)
I had the CZ-75B trigger lightened by a local gunsmith. I told him I just wanted to get rid of the "grunginess" of the DA pull; the SA was OK. He did it, and its fine. I've done very well in several IDPA matches with it.
The CZ-85B Combat (as do all 85s) comes from the factory with a smoother trigger; the fit and finish of the 85s is better than the 75s. The trigger on mine, however, is a little heavier than I like. I may get it lightened, too.
Swapping out the trigger will not improve the weight of the trigger; new springs and a lot of polishing (and stoning) is needed to make it lighter and smoother. (The trigger adjustment has to do with overtravel only -- and I'm not sure just how important that is for anything but serious competition.)