I've just bought a pair of Ms2's second hand so i should have them sometime next week. I also own the Ms1, Ms-Pro, (had to complete the collection), and also the Grado 80i and 225i so i will let you know how they all fit in line. My current order of preference is the Ms-Pro, Ms1, 225i, and 80i in that order, so i suspect the Ms2 will drop into 2nd place.
From what i have read, and looking at the response curve i really don't think the PS500's would be my cup of tea. I am very interested to try the RS1 so might pick up a second hand pair at some stage.
That's interesting. I put the SR-225i a step above the MS-1i, which I here as very close in quality to the the SR-125i. I hear the 125i as just a bit better than the MS-1i, which in turn beats the 80i by a wider margin than it loses to the 125i.