Re: fair swap ??????
To say around £600 for a BSB and to put it on the same level as a DBK is flat out false. Even if they were, DBK's are starting to head up in price. Each DBK I've sold have gone for around the £800 mark.
I've had a few BSB's over time too and each one has sold for at least £750, I even had one that maxed out at £850 + shipping and it wasn't mint (though in very good condition.)
Plus, look around this very site. BSB's are very popular guitars, most people love them. I'd jump at the chance for that trade.