Personally, I opted for a second 980ti at the £350 mark (£370 actually, for a Hybrid). I would love to think I could bypass the 1080ti and wait for the next, but that upgrade itch....
I honestly couldn't sell my Classy for £350 and then have to put another £200 to the proceeds in order to get a card that betters it by so little. So SLI was the only option in my mind.
Sorry but my immediate reaction to reading your post was yeah I`m going to the bay for SLI.
You wicked person !