Quick Update on this topic incase anyone was in the same boat as me looking at the 8'6.
After spending a couple of months getting used to the 8'10 and loving it I couldn't pass up the opportunity when an 8'6 came up for sale.
Long story short I have now found my favourite SUP ever in the 8'6, I was actually really surprised how easy the transition was, sure its a little harder in the wind and chop but not so much that it ruins a session and the performance on the wave more than makes up for it.
After worrying about whether I would be able to use the 8'6 its now my goto board in just about all conditions and am now looking at the 8'2

so if anyones got one for sale please let me know as Im super keen.