I have a similar mounting arrangement but with the PIAA 1100's. I have a set of TT HIDs on my F800GS because it only has a 400W alternator. I am now on my second set of bulbs, had water in both of them, lots of similar problems noted on the net.
There are some other options that use standard HID bulbs instead of the MR16, not sure if any of them are worthwhile, nothing posted, but I'm going to swap out my TT's if the bulbs take a dump a second time.
I think that switch is a pretty cool idea as well. This is my setup, I used the BMW switch, a little pricey, but it is integrated, and the light has burned out finally on the switch.....
BMW Light Switch
TT's on my GS. I changed the mount and went with a light bar to reorient them to vertical. The cable going into the lights were sealed with RTV and the interior of the housing was bone dry, only water was in the lamps themselves, I think the problem was with the MR16's, not the the housing, which is well made and very compact.
2007 K1200GT the road beast
2009 F800GS - My little adventure bike.
2007 F800ST - Her's, but I can ride it.