Thanks everyone for the mass of info. It gave me some leads to follow up.

It seems to me that all flatbed scanners, although they differ in quality, will have the same problems, this being the focus plane / newton rings conundrum.

So I think i will go for the least expensive option. From the images made with preliminary scans, I'll choose an exhibition and splurge for drumscans on those choices.

I would almost go for an old Duoscan which is on sale here in the UK for next to nothing, - but it only has SCSI connectors. Or perhaps an older Epson Precision, but it might be on its last legs.

So I think a newer Epson 4990 will be best.

Glad to see they have made the light panel of these newer generations of cheaper flatbeds big enough to illuminate 8x10!!

Thanks again everyone.

Chris