Ok Richoa I'll give you some idea on the numbers (bit like pulling ur pants down in public) (lucky I'm big)

I've never measured how high I boost but I'm sure I'm more of a 10m man than a 4m kook on average when I'm comfortably lit on my XR 9m with most landings smooth, not all.
Having landed 10m jumps with a smooth touchdown I feel my technique is sound (pop then send)
Consistancy isn't always there but some things are beyond what you can control, like getting f*k#d over on takeoff by some chop or fatigue or testosterone overload :)
On the 8m Pivot when there is enough wind for at least a small jump of say 7-8m, I feel like I am 3m kook with the kite in front of me rather than above me.
I think you could be on the money with the Pivot being a more technical kite requiring a skilled operator to boost well and perhaps a slightly different technique required to the XR, like a lot more speed etc.