Well, got the M9PG2-GM's on Saturday (happy birthday to me), and I have mixed feelings about them. They forced me to see the lack of range (or maybe soundstage?) of the CX-150's, but on the other side of that coin they left me unimpressed with the lows. They were very accurate, but lacking in depth. Nowhere near the rich lower ends produced by the 150's.
So, the search continues. I still intend to pick up the IM50's next, as those seem like they'd be an upgrade I can really sink my teeth into.