Extremely well built skimmers, kinda hard to tune in if you dont have the automatic washdown system which I would highly recommend. If you are seriously looking at an RK2 I doubt that there are many other skimmers that would compete.
My buddy has a 100PE that has a very good washdown system that is just amazing in performance and how clean the skimmer stays.
I'd say if you have a large enough system the RK2 is probably your best choice, and I have no problem recommending them