[JAVagueArgument]

I think geographical location makes no difference, because If it were me I would ask them for what I was currently on. Not take a pay cut, but not expect an increase either.

With the lack of security in a start up I might also ask for something in my contract which meant if the product/company were successful I would get recognition (financial or otherwise) in relation to my contribution.

[alexchamberlain]

I can't speak from experience, but how about asking them to match your current salary and a equity share to account for the risk?