Re: Advantages of 12 inch speakers...
I guess I'm qualified to respond. For the past 10-15 years, my rig has included a 2x10, 2x12, and 1x15. Sometimes I had two of each. They're all fed seperately, so I can vary the volume and tone to each. I like the blend.
I've done plenty of gigs with just the 2x10. They can completely handle the lows, but they can't push the lows out very far into the room. So for miking and close range stage volume they're fine, but you need a resonating 4x10 if you're going to use 10's as a room filler, and expect it to deliver good, deep lows. 10's can definitely do it, but they need more mass than just two in a small box. With 10's the bass stays tighter, too.
As others have said, 12's are great simply because they have become the standard, but also they cover the entire guitar range very well. A single 12" is enough to be "full range" for a guitar. But I don't like 4x12's, because they're too boomy and boxy. I like a tighter low end than what you get with a 4x12.
15's are tubby. They have a fat, round midrange, and still deliver adequate highs for guitar, but as stated, they're a little slower. So if I had to use one cab, it would be a 2x12 or maybe 4x10. I used just a 2x15 for years, too. It was great, but inadvertently became my "secret signature" sound. And in the end, I didn't want that. I couldn't get the modern "arena rock" attack and tone of the day, no matter what I did with the EQ. It was the cab. But it did begin my love affair with the 15, so I've had 15's in the rig ever since. A 15 for guitar is great, but it boxes you in to a certain kind of tone. With 10's and 12's its a little harder to tell what a guy is using. But I could always hear a 15 on guitar, even after it's been recorded and mastered into a track.
Right now I generally run the 10's with crisp highs and tight, conservative lows. The 12's are wide open vintage crank, and the 15 is deep, soft lows.
If I want a Fender Champ sound I can go just to the 10's, if I want heavy, thunderous lows I can "subwoofer" the 15, (holy cow if you've ever played distortion guitar with a sub you'd pee your pants...What bass player?) and if I want vintage 12" vibe I lower both and focus on the 12's.
And yeah, crap speakers come in all sizes. Amp/cab mismatches are plentiful out there, too. You can't judge speaker size without knowing how it fits into the total equation. A Fender Champ wouldn't sound right feeding a 2x15, and a Mesa Recto wouldn't sound right feeding a 2x10. They both might sound awesome, but not the way the amp is "supposed" to sound. But the size of the individual speaker does not correlate to low end presence. Just remember that. Home theaters use 10's as subs sometimes and it's thunderous. One bass player used an SWR 8x8" that was huge, because of the way it was ported and sized. It had chest-pounding 30hz low end. The low end travel is related to overall speaker cone mass so 4x10's would push more lows into the room than 2x12's, all things being equal. The 12 might have more lows going into the microphone, but not at 40 ft. away.
EDIT: By the way, ES350 said everything I said in just a few lines. You can skip my whole rant and just go back and read his post. :8: