~2" lift, ACE is fine. Go to 3" or more lift and you will want to buy a pair of front downlinks and put them in the rear (they're about 3-4cm longer). This will help to set the angle at rest for the active bar close to stock. THere might be another option for the front links, like adjustable disconnects, but this is still an unknown.
So far, other than a minor pipe leak and changing the fluid every year or so, no other maint. The dealer tells me to come in and do a TestBook flush (apparently it can reverse the valves in the valve block), but I haven't done it yet.
Some have said that changing out the fluid will help alleviate the groaning, I have not found this to be the case, though mine does not groan loudly.