I'm not a big fan of twisting myself but I'm not seeing how it's any different than the W200.
Yes its the same with the W200. Except the W200 has 3 ( or 4 in my case ) O rings and they can easily be checked each time you change the batteries.
When you turn the head the head moves closer to the body. This reduces the internal volume and so all other things being equal the pressure will rise. Sure its not that much. And maybe its of no concern. But it does happen and needs to be considered.
I do have another focusing system design floating around in my head and it also changes the pressure in the head but not by as much. But the focusing system will also be effected by the pressure differential from out side to in and as such may not work in a dive light application.