How much would independence cost Scotland?

The LSE's Centre for Economic Performance has published a report suggesting that independence would hit Scotland two or three times harder than Brexit: https://cep.lse.ac.uk/_new/publications/abstract.asp?index=7714

This is, of course, disputed by the SNP who argue that an independent Scotland would be able to attract more inward investment.

Much would depend on any independence settlement, but I would expect England to strike a hard bargain.

This suggests that there might be a case for a two stage referendum: one on the principle, and one on the negotiated settlement.   Of course, as we know from Brexit, identity politics can trump economic calculations.