The increased cost of CORE is close to the same as getting a slide milled. The real difference is whether you have chosen a certain red dot sight and are willing to dedicate the gun to that sight's footprint. If not, and you want to change to different RDS's, then a CORE might be better. However, the generic CORE mounting is considered by many to be inferior to a milled slide.
The new 2.0 5" has a loaded Chamber Indicator, I believe, that would interfere with milling the slide. I'm not sure if the 4.25" slide has the same LCI. So before buying a 2.0 because of the improved trigger, check to be sure you could mill the slide for a RDS.
The preferred co-witnessing iron sights placement for a number of reasons is to have the rear sight behind the RDS at the back of the slide. Some competition guns are set up with no backup irons, but personal defense guns should definitely have elevated backup sights. 2.0 sights are standard height, so you would have to replace them to co-witness with a milled RDS.
Thus, you cannot base your gun choice simply on the improved trigger on the 2.0 if you also plan to mount an RDS. There are additional mechanical and financial decisions needed.
Since the 2.0 may not be RDS friendly, and the original standard model has a sometimes ok trigger, but often a crappy one, maybe you should look at a Performance Center gun with the improved trigger. Here again, the increased cost might be a close trade off if you get the standard model, install APEX trigger guts which will be better than any factory trigger, mill the slide for an RMR, get suppressor height sights, and you will have a top tier fighting handgun. It is the most expensive route, but the total increased cost over the CORE/2.0 proposal would probably only be about $250, depending on which sight you choose.
Sorry to complicate your decision making process, but there are more factors at play here than your original post indicates.
