Originally posted by veato I'm more concerned about dust than light leaks
That's certainly a valid concern. This is purely anecdotal, but I use this technique every once and a while with my K-01 which I use every couple months. There is no visible dust on my sensor.
I've only used the technique twice with my K-3. I use my K-3 weekly. The sensor is filled with dust (until I bought an Eyelead gel stick).
I cannot use this technique with my Ricoh GR because it is a point-and-shoot. I use the camera about once a month and keep it in a sealed bag whenever not in use. I've sent it in 4 times to get the dust cleaned off it's sensor, and it currently has dust on it's sensor.
In short, I have cameras that are dust magnets, and cameras that haven't gotten dusty even after free-lensing.
This technique aside, I do everything in my power to keep dust off of my gear. Using gear will lead to dust, changing lenses will allow dust ingress, as will this technique. But these are the things we do to get the shots.
Also the Eyelead gel stick is amazing and easy to use.
I'm not trying to convince you to do it my way, just sharing my experience.