I have flown with my Exovest twice recently, with two different cases. To clarify I have the full size Exo, not the Exolite.
The first time I flew with the vest built normally inside the soft case, with that inside a Pelican Storm iM2975 case, without foam:
Since I had the soft case as padding and also had clothes in the case, the vest was plenty protected. Personally I like the latches on the Storm cases because I find them easier to open with the button-release instead of just the latch.
The second time I used an older, small case, a Pelican 1620, again with no foam:
This time I flew one direction with the bottom section of the vest taken off, turned around, and put back on upside-down (trying to attach a picture but having trouble). That bought me a little more room in the case, but the vest is slightly less stable that way, so on the return trip I packed it in the normal configuration. "Normal configuration" for me is a small form factor to begin with since I have a short torso and small frame, so the vest was in the smallest form it could be in to fit in this case.
Both ways (bottom upside-down and normal) were fine, and both cases worked great. If you're able to, find a local rental house that will let you test out a few different cases so you can find one that works for your needs before you purchase one.