The problem with these T mics is, as you note, they're not designed for music recording, which begs the question of, why you are using them for music recording to begin with, other than convenience. Although as you say, you apparently were happy with the T-mic and the MTII, but I have to agree with you that that seems to be just dumb luck. You results with the M10 sound more typical.
The published specs of the Sonys are terrible and the actual results of them tend to be, in my opinion, even worse. The SP mic has better published specs, but I'd worry about that 105dB max SPL limit that it has. While that - or the higher 120 it lists if you use a battery box - is technically sufficient, I would worry about that mic overloading.
I don't know if he still does it, but I believe Chris Church/Church Audio will do a "T" version of the CA-11 mics that he makes, which are actually designed for concert recording and are infinitely better than the products mentioned.
Otherwise, before I used one of those mics, I'd use the internal mics on the M10. I've never used them, but people say they're pretty good.