Not normally known for eating pistons, normally tensioner/timing chain, carbon build up in the valves and sensor issues, if you are up for a challenge and dont mind throwing 550 quid away then go for it, otherwise leave well alone.
Is it the N14 engine, same as in the R56 Cooper S?
Yes, that one.
Think I've got the message, I assume the vendor has been told similar hence what looks like a bargain price. Will leave well enough alone, thanks for your help all!