Great topic.
I have been running 2 REL T9is for a few years. Setup, now, is a breeze. I could turn them off and reset them and have them integrated again in 15-20 minutes or so. At first, however, I had trouble because I kept fussing with them. As I gained more experience, I picked up more intuition and my ear got better trained.
Disclaimer--I only use them to bring out the lower octave or so. I have them tuned so they are not particularly audible.
The difference with the subs is remarkable and I would never go back to not using them in this setup.