The problem with the full oxygen kits is that I almost certainly wouldn't be able to take them on the airlines with me when I fly back home after the delivery. They are an expensive bit of kit to have to abandon. I have enough problems trying to get the airlines to let me take home my lifejacket (even though it is just like the one under the seat), and sometimes my portable airband VHF and EPIRB. The disposable kits are interesting because I could just bin them after use and not have to worry about having them confiscated.