I'm in a fortunate situation where I get to drive both. My Gordini has the standard set up and the girlfriend's 133 has the Cup chassis.
There are two noticeable differences when driving the car day to day on the road. The Cup chassis does feel more eager to turn into a corner. The steering does feel that bit sharper, I guess because there's less give in the suspension. You can really feel it on even the slightest direction change, not just when giving it some on a series of bends.
The other biggest difference is the harshness of the ride. Now I'm used to driving a car that was very low on coilovers and by comparison the Cup chassis does feel more forgiving. Having said that, I think it's a harsh ride for a modern car and as a passenger it actually gets annoying!
All that said, the standard Twingo 133 chassis is equally good. It has the same levels of grip and during day to day driving it'll would easily keep with a 133 Cup. If anything with the extra forgiveness you get from the non-Cup suspension, you may find it's actually more stable on a bumpy road.
My conclusion on it? Get the Cup chassis.........for those gorgeous 17" rims. Don't be fooled into thinking a non-Cup'd 133 is any less competent, if anything it has it's own merits but I wouldn't be without the Cup style rims. Hence my Gordini not having the Cup chassis but obviously comes with those wheels.
As for handling, on a track the Cup chassis would be a no brainer as you wouldn't want the compromise. On the road, yuod do just fine with either set up.