The Stylus XS or RS has the same engine as the Geo Storm GSi either a 1.6L DOHC (90-91 XS) or 1.8L DOHC (92 RS). The Stylus XS/RS has a better handling sway bar setup than the GSi, though it is probably a bit harsher. The Stylus was never offered here with a turbo or AWD, but it possible to swap the required Impulse RS parts on to any of the FWD Storm/Impulse/Storm/Sunfire/etc. models.
The Isuzu rear struts are more expensive than the Storms. The sway end link bar tabs on the struts is different. The tabs on the rear KYB for the Geo break off fairly easily (at least with this bar they did.)
The rest of the suspension is very strong--all tubular steel arms in back. I try not to compare it to the stamped junk pieces on the back of my BMW.
They are a bit front heavy. The GSi is definitely slower than a DOHC Saturn around an autocross track. I expect the Isuzus would be a good deal better than the GSi. Steering ratio on the GSi was probably too fast, but it felt great. The 1.8L DOHC was wonderful. The GSi always seemed fast.
Body rust is a big problem for these cars at least around here. Southern cars seem to all have peeling clearcoat.