the bar pressure on the 17 is less than the x4 16 (i tried both back to back yesterday) it turns nicely for a big kite but is slow like all kites this size - heaps of grunt.
Give the 8 a miss unless you want to sail in 30+. I'm 85kg and hold the 10 in 30-32 powered but ok.
have to agree the spectrum 2 are an excellent package im 86kg and now riding the 10 and 14 and that pretty well covers me for most winds. give them a try i think youll like em!