Noooooo! We paid fortunes in SD on our purchases. I don't want to have to pay it again when we sell to downsize!
More seriously, I guess the point is an indirect sidestep of the bank lending criteria. If the price of the house is, say £1,043,750 including SD then the borrower will presumably be able to borrow 85% or 95% or whatever of the inclusive figure whereas if the house iss priced at £1m PLUS SD of £43,750 then the buyer will only be able to borrow 85% or 95% or whatever of the £1m, and will then need to find another lump sum for the SD. It puts bank's assets more at risk because the new owner (where the bank's security lies) immediately owns an asset worth potentially less than the mortgage (if the house is over about £1.5m and the mortgage is significant), and certainly less than they paid for it. Seems crazy. Loosen bank lending criteria openly if that is the right thing to do. Don't bring it in by the back door.