I had O-Rings on my Deck 82 Toxic (MX Blacks) when it was still in my possession, and liked them, but as with many things in this hobby, very subjective and varies from person to person. I think since those were such heavy switches, it had turned me into a more aggressive typist, and the difference the O-Rings made was huge for me.
Just to give them a shot again, and because they were cheap, I jumped on the Massdrop buy to try them out on CM QFR. Doing all of my development work at home, and having my desk in my bedroom, I spend some late nights working. IF there is a way I can not be so intrusive and noisy when I'm doing my work, I know my wife will appreciate it a lot. It might end up that I don't like using them on this board, but for the 7 or 8 bucks I think the buy ended up costing, I'll spend the time putting them on and trying them out for a couple days, no big deal.