I'm expecting baby #1 in November and need to get a convertible car seat for my 2006 MCS...will use it rear facing from newborn to max weight limit before changing it to forward facing. Any recommendations for covertibles sold in the US? I'm considering the Britax Marathon but have seen mixed comments as to whether it will fit the MCS. I'm also considering the First Years True Fit. Any one have any experience fitting/using either of these particular convertibles in their MCS?

Thanks!