I have the samsonite oyster. I found it at a thrift store for $7 after much searching. It is quite tricky to fit my helios in it. I am not sure if I'd have figure out how to fit it all in unless I'd found directions from someone who had worked it out. It is enough of a pain to get in the case that I worry about TSA getting it back in if they ever unpack it. To that end I pack detailed packing instructions in the case with a bold note indicating what they are. I still worry so I include my cell number.

Many domestic US airlines no longer charge oversize fees for bikes. They fly as one of your regular bags with no extra fee. For many folks that may eliminate the need for worry about case size. It may even eliminate the need to take a folding bike at all if baggage fees are a major factor in that decision. I choose airlines that offer free oversize baggage for bikes even when not flying with one.