Well i have Matrix Infinity v1.93 at PS2 Slim PAL SCPH 90004.
I can play PS1 Original games (i tried MGS1 at NTSC)
I can play PS2 Original games (tried MGS2,MGS3 at NTSC, WRC at PAL)
I can play PS2 backup games (tried Finding Nemo,Kingdom hearts)
I CANT play PS1 backup games (tried Crash Team Racing,Silent hill and Abes Exodus).
I used force PSX at the beggining,Also the games are burned in CD's
If i am not wrong Infinity should be able to play PS1 backups correct?