I have been doing just that. I have a clean install backed up, and I add something and play with it. So far what's causing the crashes is down to the HD textures that come with CryENB or CryENB itself. I'm more leaning towards the HD textures at this point, but have yet to prove that.
I have now modified vehicles.img, carcols.dat, handling.dat, vehicles.ide, as well as dsound.dll and scripthook.dll to run the simple native trainer and traffic control scripts.
I have been able to play a bunch of missions beyond the normal time before it would crash with no crashes so far.
I will continue testing and see what the cause is. I would really like to be able to keep CryENB, the game without ENBs does not look even half as good.