I would agree that a 10'6 could feel like it carves harder / bigger turns... As you go smaller, you introduce a little more 'snap' / 'snapability' into your turns, aswell as carving turns.
Watch Jordy Smith in Red, 'heats on demand'.
quiksilver.com/surf/events/pro-france.htmlHe's about 6'2 tall and over 85kg. He's probably riding a 6'2 or so.
Check out his carving turns, and also the carving round-house cutbacks, or HACKS !! Plus some good 180 degree snaps.... It's these snappy turns that SUP's just don't do well (not to mention the barrel rides : ) ), and if you do manage a snappy turn or two, you'll have little speed speed left and it will be time to dig in for a big paddle stroke.
www.quiksilverpro.com.au/heats.aspx#/154/240/Watch Kelly rip it up too.
If you are an SUP Only surfer, watch the short board guys for inspiration.... you can do similar moves, but just not as radical, not as vertical, not as deep in the barrel, so as tight in the pockets, not as snappy, not as many moves per waves (but these guys are pros !!!), etc.
I tell you, I'm almost as happy riding waist high waves on an SUP (on the protected points) compared to overhead more exposed point breaks on my shorter boards.... I prefer the big point breaks, but once the wind picks up and goes onshore, those protected spots can be loads of fun, especially in the knowledge that the other breaks will be big rubbish.
As much as anything else, it is about;
getting wet,
getting some sun,
riding a wave,
and having fun,
5'11 or 11'5,
who really cares....