What bags are you guys using to check the housings etc.? The old standby Samsonite Flite that the pelican foam would fit in is too big now.
For an upcoming trip to Indonesia I just purchased a Samsonite 28" Flite upright, $116 shipped to my door. At David Haas' suggestion I bought the Pelican 1625 foam set that is designed for the 1620 case (~ $150 from B&H) It looks like it will work VERY well. (Thanks, David!) Luggage dimensions are 28" H x 20" W x 11.5" D, and weight is under 11 lbs. With the pelican dividers I can put an Ikelite housing, two Ikelite DS-160 strobes vertically, an 8" Ikelite dome upright (!), with loads of room for lens, ports, cables, flashlights, tray, handles, arms, clamps, and chargers for everything, mask, and a keeper box for o-rings etc., still well under 50 lbs. It rolls well, looks very ordinary (in a good way), and is very stable when upright. I'll post a photo with text indicating what fits where. I bought it from this place, which shipped very quickly (but out of stock as I type this). Really, I can't think of anything significant that I would change on it. Maybe another handle? The great thing is that it is deep enough to put so many things on end, using the full height/depth of the Pelican foam set. There is enough room outside the dividers to put all the really dense tough stuff (tray, handles, arms, flashlight & batteries) at the end that is on the bottom when turned upright, which makes it very stable and easy to roll when upright.
I've got a rolling duffle (5 lbs empty) for fins, wetsuit, booties, BC, regulator and clothes. I'm using a Lowe backpack (CompuDayPack?) for carryon, with laptop, camera & 18-200 lens, and travel essentials. With a photo vest I could make it very light if need be, probably even getting both pieces of luggage to 20kb/44 lbs if I really had to, and of course a second piece of luggage may cost me, but if there another flaw in this scheme, please let me know. It has all the useless perfection of a plan that has never met reality.