Britax Marathon or Britax Decathalon?

I need a car seat that is safe comfortable and FAA aproved, i have narrowed it down to a marathon or a decathalon. I would like some opinion from owners of both so i can make a proper decision since they are pretty spendy.

We have 2 Marathons that we love! They are both great seats that are comfortable, safe and FAA approved.

Here is info from Baby Bargains:

The marathon is the first and most basic. It features 4 harness heights, double straps anchor attachments with bars (instead of using the belt path). It can be tethered rear facing and used rear facing from 5-33 pounds and forward facing from 20-65 AND over a year old.

The decathlon features additional infant padding that makes this a very plush seat and very supportive for newborns. It use a single anchor strap routed through the belt path. It has 3 different crotch strap settings and 4 harness heights. It can be tethered rear facing and used rear facing for 5-33 pounds and forward facing 20-65 pounds AND over a year old.