Since the virtual elimination of joints on plain line, railways out in the open have been remarkably quiet anyway; but the row on underground lines, particularly tube lines is spectacular. As a kid, it terrified me and fascinated me in equal parts. It must be a hazard to hearing, though, particularly to staff over-exposed to it. It has to be worth a try, this product. looks both affordable and simple to apply.
IIRC, there is equipment that is actually located differently in an s7 to an s8. I can't see them changing the seats around, and leaving a single train with equipment in a different location.
Quite frankly, I can't see them doing anything except continue to run an occasional train with all-longitudinal seating. The difference is marginal. If a few passengers switch to Marylebone, then so be it. From what I read, there are bigger incentives. This issue of the Met service dropping behind in speed and comfort has long interested me. During the early May bank holiday, I had planned to travel from Marylebone to Baker Street via Amersham, to make the comparison. Regrettably, and for family reasons, the trip was commuted to Denham Golf Club and return; and even that didn't take place due to timetable difficulties. I have some ideas, though, which I'll be working on over the coming weeks. Thanks to domh245 for the link to the Rolling Stock Info Sheets. I now have something to work with.