The only differences between SVT seats and standard seats are (as far as I'm aware): The SVT has a micro-adjust recline on the inside of the seats and the standard seats have a tilt adjust on the outside of the seat; the fold-forward release is on the top of the front seat back on SVT's and it's on the bottom back outside of the seat on the standards; the SVT seats have a power seat height adjuster, while some of the standard ones have a manual seat height adjuster.
Do you already have a set lined up, or are you just looking? Remember that you have side airbags on the SVT, so if you buy a set of seats without them, you will need to address the airbag light problem. I've done the reverse myself and swapped a set of SVT's into my 2000 ZX3 with no problems to speak of. I can't imagine downgrading the seats would be any different.
2000 ZX3 Autumn Orange - faithful companion
2003 SVT Competition Orange - new playtoy