Well being one of those guys on that thread :-o
I run or have run Photogenics version 5 on Windows XP ( windows native version), Amiga forever (3.1 Amiga version)
A4000 PPC/060 with Picasso IV and OS3.9 and currently a MicroA1 with OS4, I've had the odd glitch on all OS versions but its hardly unusable I mean what software doesn't throw a glitch every now and then :-D
It could do with being Updated sure, maybe Discreetfx might ask Paul if that's possible by a 3rd party
( on the Amiga side I have had every version)