I had a similar experience with my Street Scrambler- the heat reduction was significant to say the least! Well worth the h-pipe for that reason alone, as well as de-constipating your bike!
Re the m.o.t issue, my Triumph dealer fitted the x pipe to my Speed Twin, They will be doing the M.O.T when the time comes, I would be annoyed to say the least if they failed it! Pretty sure it’s not a problem! Also my stone guard does a pretty good job of hiding it.