I am loving the MT-10 so far, went thru 2 other types before the MT-10 and am thoroughly impressed with this model. I did a 3 week out and back trip in it from Minnesota to California and back hitting Colorado, Utah, Nevada and it handled it like a champ. The frame and suspension system seems to be up to anything I've thrown at it within reason.
The MT-10 uses Intelli-Core structural composite sandwich panels and I tested them with a scrap piece from Escapade before thru bolting my Pelican case shower station to the outside. Properly inserted nutserts with the proper installation tool are solid and although you could crush the panels with a bolt and standard washer/nut combination, you would be seriously torquing them to do it, a large area washer eliminated that problem and I have 6 of them holding my shower station on along with 6 nutserts and bonding so between all 3 it is solid and you could probably lift the trailer. My tools are only attached using nutserts with no issues.
The floor and ceiling are thicker panels and also utilize the Intelli-Core material. You are able to walk around on the roof with no flexing.
The Truma was not available and I have a few buddies using the Propex's so I was comfortable utilizing the Propex. I don't think you could go wrong either way you choose.
Cheers