This may be a silly question...just had a puncture, small hole in tread. Didn't drive on the tyre. Should I repair or replace? Anyone had bad experiences with repairing punctures? Should you ever repair punctures on high performance tyres? Any comments greatly appreciated (ASAP??!!).

I have repaired two or three times punctures on my old car which was wearing Michelin SX-GT tyres. There was absolutely no problem afterwards. The tyre is left for a few minutes in a device that heats the specific point where the puncture occured and the tyre is (almost) as good as new.
Also, deciding to change the tyre will cause problems as you will almost certainly have to change both tyres and you will have a car with a pair of new tyres and a pair of used ones.