Repeating some of what I posted above:
Both the M&S we originally had on our 24 foot Itasca MH, and now the current M&S2 set on it have been absolutely outstanding .... except for one little thing: The M&S set wound up with cracked sidewalls in only about 5-6 years, WAY BEFORE the tread was anywhere near gone.
I'm hoping that our current M&S2 tires - with their different/new sidewall material - do not ever develop sidewall cracks. I'm assuming that fixing of this problem may have been what Michelin at least partially had in mind when going to the new sidewall material formulaion.
Note that M&S2 tires have a longer warranty than the M&S tires - 60,000 miles for the M&S and 70,000 miles for the M&S2. I also went to a new tire size when I switched to the M&S2 so that I would get a Green X rated tire for less rolling friction. The new size also provides better ground clearance and better air flow between the sidewalls to help keep heat down in the two rear dual sets.