Quoting CerealMakerWife♥:" I honesty think the Harmony is probably your only other option as of right now. That or get a slimmer RF seat."
I considered that, but my older kids will need spare seats for my mom's car anyways. DS starts school and she's picking him up after school a few days a week because DH & I work out of town, and she is taking DD every day instead of daycare because I'm unhappy with her daycare situation. It would be a total pain in the ass to have to switch their car seats in and out of my car every day... so I might as well get new ones.
The Harmony Defender looks like a piece of junk, though and is incredibly ugly IMO. I like the Radian seats, they used to have them when they were younger until I totaled my car- but I really don't need to be paying for the RF option that they won't use.
Gah... guess it looks like I'll have to go with that seat anyways. Maybe my younger kids can get some use out of them, too?