Infinity v1 or 2?
Why not go the screamer 10? Incredible range... At your weight it's good for 15-35 (I weigh 65kg and have had it out in near 40 knots) 30 will be comfortable at a guess. I only get my screamer 7 out if its holding over 30 solid. Slightly bigger wind range and unhookable up to low 20s for me so maybe mid 20s at your weight? So that would lap with your 2 kites!!
If you do want a c4 though 11/8 combo?! Never ridden the infinity but from what I read there a handful once you hit the teens, depending on your average winds this may leave you with a big gap if you go for something smaller then the 11.
Ive got the v1 infinity
ive been using 3g renegades up until now but ive decided I want a change. Ive tried the 10m S LTD and realy liked it. We have still got epic demo kites I can use so if I want a big boosting day then I can get out the Screamer 9m