So I can’t compare the 1502 to the 275, but I have a MC2000 and a MC275 Anniversary edition. It seems like the 1502 is somewhat of an updated version of the MC2000 as best I can tell. The 1502 is rated a bit higher watt-wise but the 2000 has been measured to actually put out close too the same amount of power. The 2000 is also dual mono where the 1502 is not. The 1502 has a 12dB higher S/N ratio, not sure how much that matters. The 275 is 5 dB better than the 2000 but the 2000 blows it out of the water.
From what I’ve heard about the 1502 and pretty much all the new MC tube amps from the last 10-15 years is they sound more solid state than tubey. This has kept me from upgrading my amp (and money LOL).
Both the 2000 and 275 have a wonderful tube sound. The 2000 blows the 275 out of the water though in sound stage, clarity, robustness. Both lack in bass AFAIK which is why I’m bi-amping my B&Ws with a solid state for the lowers and the tube amp for the mid/highs.
I would love to hear how the 1502 compares directly to the 2000 but I’ve as of yet not seen that, probably because so few 2000s are out there.