I am going to buy a carrier for my trip and thought I'd get the soft type roof carrier until I came upon the "car back carrier". It seems possibly better not having the airdrag issue, but I wonder if its not too awkward in getting in to the back of the van. I'm assuming you remove the sack to get in to the trunk of the van etc. So maybe the airdrag issue wouldn't be so important if your constantly frustrated with the back carrier getting in the way. I would really appreciate hearing from somebody who has experience in the use of possibly both types.