I have this same 2x12 as well. I really like it, although I find having the Mesa logo smack dab in the middle sucks when playing with different mic positions. Get your screwdriver ready.
The "sweet spot" for me on my specific cab is actually right at the bottom left-hand corner of the mesa logo/plate; which ends up being right on the edge of the dust-cap and cone pretty much. Straight on, about 1/4" away from the cloth. I actually find that the mesa plate pushes some of that low-end into the mic keeping it right at the edge giving it some weight. I don't have a treated room I'm mic'ing the amp in, and have lots of neighbors, so I can't turn up my 5150 past 1, so this position at that volume level works fine for me. And I love how well this cab responds to bass and resonance... it definitely growls!