Well, the Radian does have some issues, but I think there are less than sometimes comes across on the board. Yes, be cautious, but not too paranoid. I love my Radian (well DD's) and the only car that it doesn't install well in at all with the seatbelt is my Saturn Vue, and it has LATCH in all three back seat positions, so it's not a big issue for me. I have had it in at least 10 different vehicles. (We have three, plus visiting multiple relatives, etc.) If you have seatbelts that come out forward of the seat bite you are likely to have problems, worse with the Radian, but also not great with other seats.
It's a little "different" just because it's really heavy and I have to give it a good "knee and tug" to get it tight, but it's really easy if you are used to it, or just used to installing seats really tight all the time.
So far, now that DD is FFing, it's my favorite seat. (I have a WZ, which I like too, and a Chase.) I'm getting a Young Sport for our other Jeep Wrangler so I'll have to see which I like better, although I'm sure I'll probably like them both for different reasons. I like the idea of true SIP for our Jeep since she has to be outboard (and the WZ will be used by baby), but if I couldn't buy another seat I would use the RN in there too since it installs great. (seatbelt, it's pre-LATCH)
Anyway, that's just my opinion. I wish I could bring it over and try it on your car for you!