Never really tried the 12'6'' as the only board I've ever owned is the 11'2'' and I love it! I'm a complete hack of a surfer but within a short time (1 or 2 sessions) I'm catching waves! Its nice and stable, easy to catch waves and as greeny would say, "it's got soul!!"
I reckon its likely to be my first and only sup as i've got no need to upgrade to anything else. Hope that helps!

Yep I too have the same board as Hawkie and yes it has absolute soul.
Im the same also where I wont be getting rid of my SB 11'2 UB or even getting a new board soon.
IF I was to get another board it would be the SB 9'8 or the Naish 10'6.
Any smaller and Id rather be surfing

I've got both 12-6 and the 11-2, I probably use them the same amount but much prefer the 11-2 for waves. Saying that though the 12-6 in rough open ocean is much more stable and lets me paddle distance without worrying as much about every bit of chop knocking the board around. Funny thing is that after learning to ride waves on the 11-2 I've learnt so much more about board trim that I'm now able to catch small waves far more easily on the 12-6. The 11-2 is much easier to handle off the water, I've got a van and I'm shortish so the 12-6 on the roof is a bit of a performance. Summing up - you need both!