Hi Ioannhs, not the SB team here, I think the lucky buggers are all in Maui on their yearly photo shoot
Cant comment on the new 2010 iS86, but I have used a 7.6m and a 7.8m NS Warp on the 2007 iS87 a few times. It worked great with no problems at all (I'm 105kg). My mate uses his Tushingham 7.7m X15 on his iS87 and he is about 80kg.
When slalom 63 replaced the old slalom 42 formate, sail manufactures had to re-think "sail range". As a result, sails for 2009 onwards have a larger wind range to compensate for the new PWA rules. Severnes new 7m would be the direct replacement for your current 6.7m so the 7m would the correct replacement.
P.S. One of our local lads has the new Reflex in speed sizes, they look wicked