well i not been in an unoT, but i have always imagined they would be a bit like a GT but better lol - more raw. Same as i see seicentos and cinquecentos, they share so many parts they are almost the same car but the cinq is a bit lighter, and just better.
I can't see that it should feel more planted than a GT, there is basically no difference between the two bar different actual shocks and springs and the rear brakes are different. They all have the same basic setup so it shouldn't be any less or more planted than a GT with the same shocks and springs really.
Having said all that, does the 90 have the rear anti-rollbar?