I got one of each. A top condition German FL 2x12 that usually sits here in my house and I record with it, and a tatty old american RL 4x12 ex-hire one I got 2nd hand with a flight case too. That lives in the back of my van most of the time and is ready for practices and gigs and I care less about it getting any marks on the vinyl. Which is best? The 2x12 sounds really great and used to be my only one and was easier to move for everything, I'd take it over the majority of 4x12 out there, but the 4x12 does just plain sounds that little bit bigger and "thumpier" for want of a better term when loud in a noisy place so just has the edge most of the time. Maybe being RL I just prefer it slightly but I think it's the extra speakers. When I tried my 2x12 FL vs a 2x12 RL when I got them they blatantly sounded different and it was very hard to decide. IT seemed to have just an extra presenece to it I loved although not quite as 'warm'. The best was both an FL and RL 2x12 at the same time!
Either way I'd be damned if I had to move that 4x12 everywhere and it had to go up and down the stairs the 2x12 used to have to. So I'd answer the 2x12 vs 4x12 question depending how much you like your backbone functioning and how far they need to move.

P.S. I've now had my Herbert over 10 years and although I've had an odd naughty affair with other amps I'm still happily married to it. It's aged better than I have in that time...