B.B.
WE own the marathon and it is perfect but need to get the next size and my girlfriend who researches EVERYTHING to the extreme swears by the Radian 80 (or Radian 65, but might as well go for the 80) by Sunshine Kids.
www.skjp.com pr Bergstroms. This is what she wrote me about it recently
"I love it because it has a steel alloy frame, it sits lower in the car, has more rump to leg space (depth). It took a little bit of practice to get it in as tight as my Britax
(but now I can get it in as tight as the Britax). The seat is also slimmer, so it leaves more room. I seriously love it as a forward facing seat."
So this will be my next purchase she is my go to girl on items that have been heavily researched-so just another opinion!
Good luck!
watch the video it folds flat! WE traveled last year on a plane this would have been easier!