Have you thought about the boosters? I went through my last pair of stix recently and the boosters seem very similar (I take the same size in both). I'm guessing they will be going on the cheap when the new range comes out.
I'll have a look when they hit the bargain bin. In the meantime, the blurb from scarpa says this:
Vapour S - Train, boulder, climb - a super aggressive and sensitive slipper.
Instinct S - The most sensitive shoe in the entire SCARPA collection - perfect for training, bouldering and sport routes.
I'd be interested to know what the difference is in real terms...apart from the colour obviously.