Dave, I haven't enquired yet. I thought I'd see how I got on with the serrated one first!
The blade is retained by a central (plastic) knurled nut. And its driven via 3 pegs, which locate through holes in the blade's hub.
Quite apart from that geometry, the blade isn't a flat disc. Think of a shallow soup bowl with a wide flat lip. There's about a cm between the plane of the drive pegs and retaining nut, and the plane of the blade. I can recognise that such shaping will help stiffen the blade.
The un-serrated blade would have to have the exact same geometry. I'd be astonished if it fitted any other company's product.
If you think its a viable possibility, I'll happily measure it for you.
The Customer Service dept has an 0870 voice number, a Walsall address, and a normal fax number. The email is
support.uk@kompernass.com My slicer is called a "Bifinett KH 150 DIVA"
On Monday, I'll ring and see what the deal on the "special equipment" blade might be ...