3MP,
I'd run the M1, 0w-30 instead ...the cold temp flow properties are significantly better than the new 0w-20, which is actually close to being a 5w-20. The HT/HS viscosity is also 2.9 Cp, vs only 2.6 Cp for the 0w-20. I think Mobil has quite a markup on this 0w-20 - it looks like a thicker basestock than their 0w-30, but with no VI modifier added.
The M1, 0w-30 will shear down to a 0w-20 after 5000 miles in that Honda engine, so oil analysis will indicate its a 20wt oil.
I normally recommend a 0w-30 synthetic for these 5w-20 applications, since it "brackets" the low/high temp properties of the 5w-20. Even though Amsoil specifically makes a 5w-20 synthetic, I'd run their Series 2000, 0w-30 stuff in Ford/Honda/Mazda engines calling for 5w-20.
TooSlick