I think I agree with Greg here. And the initial posting on this thread seemed contradictory to me, unless I read it wrong. In my paragraph below the figures are not meant to be typical but for illustration.

AIUI Andy is saying he was offered a performer for a guaranteed fee against a percentage. Lets say for arguments sake you guarantee £150 against, say 90% of the door. So if you take less than £150 then you have to pay the £150 but if you take, say £200 on the door you pay the guest £180 (90%), club keeps 10% ie £20.

Now Andy is saying that at his club the door percentage would be low but he was willing to pay the flat guarantee. Well I'd suggest that, as Greg says, if a percentage is involved it usually means the guarantee has been lowered. If you want to pay flat fees then you need to come in slightly higher than the guarantee. Or maybe somewhere in between with a lower percentage, maybe say £170 against 80% in the above example. There is plenty of room for movement here it is a two way discussion, with a reduced guarantee against a percentage the artist is mostly taking the risk. With a flat fee the promoter is. Between the two you compromise.