I can understand where you are coming from Jmo. My bike was the prototype for the MM system and I also had my concerns that they had not used the original Yamaha frame fixings. But in their defence the framework is extremely strong and they have a rear carrier frame that fits where the top box would go. In fact it is made for their top box and is very sturdy.
I have been in direct contact with Paul from MM and he told me that there was a lot of messing around to access the bolt holes that go through to the silencer (does that make sense?) and "people don't want to take their bikes apart just to put bits on"!, that is why they decided to use the current fixings.
Anyhow as I do have MM panniers is there anyone out there that has some Touratech frames that we can try and fit the two together for Jmo?
Don't all shout at once and consider that I'm at Huddersfield, we could meet up have a cuppa and get some pics. Just an idea, but this weekend would be good.