IMO, your tone goals pretty much hits the nail on the head in regards to what the M6 (or M9) will do for you. Loud, clean and clear is what it's all about, but don't be afraid to set the gain in the noon-1:30 range, which is where I've found the sweet spot to be.
Though I personally never played through that exact head/cab combination, I also own an M6 and would think that it would be more than capable of driving that cab nicely.
As for any cons, there are a few:
1.) Master Volume goes from off to earth shaking very quickly, especially when the gain is up higher.
2.) The pull mute, coupled with the above issue, makes it almost impossible to get back exactly to where your volume was before (I use the mute on my pedal tuner to get around this).
3.) I believe the Master Volume also affects the effects loop send level, which I know has been an issue for some people who use the loop. I personally don't use the loop, so it's not a problem for me.
3.) Like most (or all?) other Mesa amps, the Master Volume affects the DI level unless you set the DI on "Pre" (which IMO is recommended anyways).
It would also be nice if there was a sweepable mid control or even better, a Para EQ, but so far there hasn't been a room where I've used it that it didn't sound great in. The tone controls that are there interact nicely and you can really dial in a lot of different sounds - very deceiving with such a relatively simple layout.