We use 2 FF. I like the headwings and the steel frame. The harness does not even tighten on one, almost at all, with kid or not. It's set to where she needs it, but it's annoying enough that I'll be happy to get a Frontier85 soon for her. She's also about 40 lbs. and that's Honda's limit. It's SL so I know I can still use it, but again, I think the Frontier at this point makes sense. (seatbelt in her seating position isn't really an option that's any good). And I could not get a good install with seatbelt in the back of my van, FF, so that was a huge problem. But if it was compatible, no problem.
Basically I've loved my Radians FF. I liked them fine RF, too.
Other than the harness, no real complaints.