I'd never travel with the camera inside a mechanically operated housing because a bump to one of the controls might damage the camera. It could break a button on the camera itself or crack the touch screen. Electronic controls don't have this problem, although my experience is that electronics have other problems
On the other hand, as you point out, putting the housing inside a carry-on may cause it to be overweight and oversize. Gates housings are tough enough, and can be padded inside the checked bag with a wetsuit.
Maybe the future will bring 8K videocameras with superb white balance etc. that are smaller than the GoPro including the housing
I put my AX100 Gates housing in checked baggage after padding it with at least one wetsuit. I put the camera and ports in my backpack along with all the batteries, padding the ports with neoprene covers on the lens sides and the plastic port caps on the housing sides. Of course, with a mechanical housing, NEVER travel with the camera inside - but you already knew that. A few fluffy things (speedos(?)) can be inside the housing to save some space.
I use the ReefNet 3D printed adapter for the Gates FP34A flat port.
I was surprised to learn it also physically fits the GP34A wide port! Thank you Burkhard!
I hadn't even thought to try that.
I must admit I'd prefer the aluminum version from SAGA if I didn't already have the ReefNet one which is 3D printed (nylon?) and not as strong as a properly made aluminum holder. I've already broken one - perhaps my fault?
I'll try this combo with a +5 and maybe the +10 since I have both. I know the +10 works amazingly with the flat port. I've put up a still from the AX100/flat port/+10 of Flabellina Dushia eggs somewhere on this site and you can easily count the eggs which were not really visible underwater.
Going to Fiji in May, so my bag will have those diopters in it, thanks.