One more comment on the PI 1800 model (I got a rebranded - Mediax - one): I simply hate it! This scanner is a total POS, I regret every single Euro I spent on it - check out my gallery: the 'Welder' pics were scanned on a friend's Minolta Dual Scan III and are quite acceptable; the toned pics are mostly prints scanned on a cheap UMAX flatbed, and are also OK; but all the newer stuff was scanned with the 1800 - look at the 'Rewolfinger' and 'Turl Rewitz' series - the quality is really bad; those were difficult negs, however - pushed film, very high contrast range, thin shadows, dense lights - but even with that kind of film the Dual Scan coped much better (as you can see in the 'Welder' series); even with regularly exposed middle-of-the-road negs (contrast- and density-wise), quality is rather low, every once in a while the scanner makes weird stripes right through the scan, sometimes I have to make three or four scans before I can get an acceptable one.
Since 99% of my films are conventional, silver-based B&W, I don't know whether results would be better with color negative or slide film.
Roman