As far as I can tell, MorphOS 2.x seems 100% (or almost, I don't remember any problem though) compatible with 1.4.5. Just like with MorphOS 1.4.5 to run Fluffy Digital Snowflakes you need to type from CLI

MWI+SPD-FDS.exe -old

Other demos that work:
Elude 68k ones, the MaWi demos you can download from here at MorphZone, Encore ones, some of the old PPC demos from Venus Arts, some old WarpOS demos from Mankind, Zero from Universe (for AOS4 using os4emu). Another native one is BX GL1 from Bluebox Cinematique (has a nice blue butterfly and a blue teme).

Kind regards,
Andrea