Pretty sure that is the case for the low end, after riding the 11.5 back to back with the 13 Waroo. It's a different feeling for both kites. The KH gets you going and are powered up, but it has less of a grunty feel.
But, the top end is prol'ly about the the same for the 11 'roo and the 11.5 KH. Al-kite-ah might hop on here eventually and give more info. He is prol'ly the best one to nail this one, since he has most sizes in all Best stuff and is about your weight.
Can't go wrong with the Kahoona, most likely. No need to get the KH bar. Sizing is always the tricky part. The lighter you are, the easier to pick sizes, imo. A feather weight can ride lighter wind (obviously) with a kite, and (if has strong legs) can hold down quite a bit on the high end. Not that riding overpowered is a good idea, because it isn't, but light weights have it easier when picking sizes, imo.
Do you have a big "equalizer" board yet? That's the real key in making a big guy have a great time in light wind or sticking to just one kite from 12 to 20, if you wanted to. Big G got a nice light wind board a while back and figured that one out.
I actually went almost a full year on nothing but a 9m from 10 knots to 30, by switching boards out, just to do it.
No problemo riding upwind in 10 on a surfboard.
That would be simply impossible 6 years ago, btw. Amazing how good (all) kites are these days. I can't even fully express the difference. I believe 90% of kiters today would quit if forced to ride 01 gear. It was pretty crappy.
We'd also have so many incidents at EB it wouldn't even be funny.
ahh... but that's not a reality and I got off topic.......