I have no experience with CZ Custom but I do have a PCR that CGW did an in house pro package upgrade. The trigger is smooth rather than grooved like factory trigger (I guess it's an 85 like Tanners Owner said), DA trigger travel is shorter, reset is shorter and both DA and SA pull is lighter. To me the greatest improvement is no creep when SA breaks. The single action has easy take up, I feel the wall, it breaks crisply and then stops with no over travel. SA pull is about 3.5 lbs.
Like you I don't care for CZ'z factory sights, I opted for Dawson tritium sights for the PCR that CGW has but I'm not using my PCR for range. If I wanted precision sights I think I would have gotten a red FO front post and rear all black adjustable sight.
Hope this helps