s0nspark, this subject about rollers is interesting. I may never take my P-09 fully apart by myself but I will try to exercise the stock trigger. I have not purchased or had magic parts installed in my P-09 9mm. I enjoy showing people that a stock CZ can shoot, so to speak, accurately. 
The nice thing about the P-07/P-09 is that they are great out of the box. You don't *need* to upgrade them to have an accurate, great shooting gun. Given enough rounds downrange and/or dry firing, the action smooths out and the springs break in and it just keeps getting better.
The reasons I do the CGW upgrades are really twofold. First, there are a handful of parts that address potential issues with stock parts. The firing pin retaining pin can break if you dry fire a lot (I do) and the trigger return spring is another part that, for a while, was a source of failure. I replace both of those just to be safe since these guns are carry guns for me.
From there, I choose to lighten a few springs (the guns are really oversprung from the factory) and, well, I end up just replacing everything LOL There is a relationship between many of the parts so when you start replacing one thing it requires you to replace something else to ensure proper operation. It is journey down the rabbit hole... but an extremely fun one :-D
