I'm always going to suggest an electronic housing as I like the controls in one place. The Seatool is by far the smallest/lightest of those I listed. Nothing else really comes close, they managed to mold their housing around the camera. I've held one, they're tiny (so are the buttons if you've got big fingers...) But the most expensive.
I believe you can separate the base from the housing on the Ikelite for travel.
When I bought my EVO, neither the Gates, Seatool or new Stingray were available. If I was doing it today, I'd take a long look at the Stingray + - and maybe buy their Bluefin instead. Cost is not so much a factor for me. And I don't have to fit it in a backpack.