Re: What speaker to pair up with a celestion vintage 30?
Negatively affects it? Not from my experience. I have several cabinets, and at one time ran a rig with 6 cabs:
2 2x10's
2 2x12's (one V30 loaded, one J.F. Naylor Jensen style)
2 1x15's
Miking the sound of one cab, while running a different speaker that is unmiked is practically irrelevant. Unless you're saying that the second cab bleeds, but in that case it would be a sound you wanted I assume. If miking both cabs individually, then you'll get a great stereo spread if you pan them, and a double-fat sound if they're panned center. If you're talking about phasing issues, they can be addressed plenty of other ways, and are equally prevalent among identical cabs. You can also spatially isolate the cabs and mic them seperately with no bleed whatsoever.
I think what Lew's saying is that no, we wouldn't "advise against" mixing the speaker types in either a single or double miking situation, live or studio.
As for the speakers, the G12 is great. My sound was always the Naylor Jensen types mixed with whatever british speaker I wanted at the time, Vintage Celestion 10's or 12's. At one time I had a smoking rock tone from the Naylors and Peavey Scorpions! Though dry, cold, and generally lousy by themselves, they stayed crisp and tight while the Naylors were bouncing and rattling away. My Naylors are from before they even named them, but they're similar to the Special design 50, with some mods.