I agree on the comparison to VTS/Gtis in a straight, line, my Mrs mk2 172 can pull away from my VTS a few car lengths on long straights, but i reckon mine will turn slightly quicker. Although it wouldn't be enough to keep up round the track, the clio is still a decent cornering machine.
Imo, the Clio is much better on high speed corners, feels more planted on standard suspension because the VTS isnt quite as well set up as standard and tends to get a little skitty. A well set up VTS is a different matter, as would be a well set up 172.
172s are great cars, and to be honest, the only reason i would buy an impreza over one is for the sound/mod-ability, because standard they aren't that much to be desired imo. The best bit about a Clio is that it is so chuckable and quite a raw hatch for this day in age, but what it lacks is grunt top end.
Look at the 0-100 times and u will see a 172 does it in about 18s standard, so its no slouch, but its after that it gets a bit breathless thanks to its aerodynamics and lack of out-right power. But lets be honest, since when does top speed matter except for pub talk?