Ok thanks folkz
I've already got the upgrade speaker as it happens so I'm going to fit it and see if there's an improvement.
If not, there may well be a speaker for sale....bought it off here anyhow
Didn't want to go the extra cab route and have to lug it around + we play small venues - standingnexttodrummerbassinBillWhymanposition - sort of thing, so there often isn't room for extra gear