No way would I trade an 8P S3 for a mini JCW.
They are fun to chuck about even standard and the cooper S we had was a match in the bends for my 8P S3 that had KW clubsports, a pair of H&R anti roll bars and an anti lift kit, but the S3 was the far far better car and engaging with those mods and 2+
The mini would also dance across the road when you hit a bump or a pothole and was very tiring even on non run flats
My mate had a 10 plate JCW at the same time (ironically from Slough mini), he hated the ride and he traded it for a Golf R and loves it.
I'd be buying the B16's for sale on the forum and keeping the S3