As said the 306 loves to LOO and is very progressive and fun, standard v standard I can only compare a GTi6 to to a 182 but the Clio feels much more sure footed. With the 306 there always seemed to be to much body movement. The 306 is proably more fun.
I had a 306 XSi 16V which the same suspension never gave me the confidence to be as committed or corner as hard as the 205 GTi I also had at the time, or the 182 that followed. Neither feel that edgy to me. The longer wheel base of the 306 tames it down a bit more when it does go out of shape over the Clio. The Clio seems to have a load more grip at the front end as well when pushing on, and just turns in. The 306 GTi has better weighted steering.
Stick a set of new boots on the 172 and have another go.