Pete Dunn of Fun's Back Surf in Cottesloe now has some of the C4 range in stock including for demo (9'0 Batwing, the 9'6 SubVector and the 10' BK Pro).
I tried the 9'6" Sub Vector down at Iso's this morning in initially clean conditions then a bit of chop as the southerly came in. Found it a bit tippy (I'm 6'5" and 95kgs) but I think that's mainly my poor balance coming off a 32" wide board.
Not much wave about so a bit hard to comment on its surfability (although it does have a good reputation in this area).