SirPoonga - yep, I realize that its the files that are off, and not the emulator. However, I just found that there were too many variables to get the "perfect" timing down. Stepmania admittedly wasn't available when I was in my DDR phase.
Unclet- I can think of a few reasons why you'd want native Playstation (PSX) compatibility for the platforms:
1) Cost - Its just as cheap if not cheaper to obtain the dualshock ps1 pads and 2 usb converters. I believe snaaake sells the ps1 pads for cheap (please correct me if I'm wrong, thanks).
2) Games - You can play alot more DDR games (eg. DDR Max) on either the PS/PS2 than the PC.
3) Future Versatility - so you don't have a ps or a ps2 now. In about one year, the ps2 prices will be 100 bucks. In 2-3 years, your nephews & nieces will be giving their old systems away to you. You might as well plan for the future now.
If the price and effort are similar, why not do the project that will give you more options? The most difficult part would be to find the right converters.
Donger