Depending your ability, they aren’t too bad. I’ve done 2 summit hydraulics kits, one on a LX and one on a MX. Both took a handful of days with a few hours after work.
In the last week I installed the Summit Hydraulic 3rd function kit and a LP 0660 grapple on my 2501. It was not completely without headaches but overall not bad. At least a few of the headaches were self induced.
As of earlier today the grapple is working fine and I've stopped the hydraulic leaks.