I'm in need of a flat-bed, high speed scanner that can handle slides, negatives in a wide variety of sizes, internegatives and APS cartridges. Not a techy, but know enough to be dangerous, & I can't seem to find anything that fits my requirements...would appreciate suggestions.
I think you are looking at more specialist equipment -- I don't think APS ever really caught on. Check out Epson -- their flatbeds used to come with a range of masks which as I recall, included sized larger than 35mm.
The other question to raise is whether the scanner will recognise a home made mask -- most seem designed to only look for negs or slides in the position provided by the supplied masks (or at least that's my impression).
I have to say that scanning negs and slides (even with a purpose built film scanner) is tedious at best and the results can surprise one -- sometimes in a nice sense, but more often not. Issues caused by age and pollution, sometimes by Kodachrome, sometimes by something as simple as a white card slide holder. And then there's dust !!
If you have a lot of material, for your sanity's sake pay a bureau to do it for you.