Hi,
I was not using the gelstick, but a similar product, that did cause me to have to send a couple of Canon Cameras back for a fix.
If the Gelstick is recommended then I guess it would be OK, however on a mirrorless camera, the fact that the sensor is so much closer and exposed, the traditional wipe/fluid is easy enough.
I like the idea for sure. On the camera mentioned X1D, due to cost, I would not use anything other than what is recommended, in this case ewipes. Just me.
I am just a bit too protective I guess, however since Nikon/Fuji both have such good dust removal sensor shake etc built in all I really clean with a wipe is my P1 back and I still don't like doing it but there are times it must be done.
Cleanest camera I ever used with out ever having to clean it was the Canon 5D MK2, whatever Canon did on that one was amazing. Unlike the 1ds MKII and MKIII
Paul Caldwell