Can we get a few things back into perspective here?
1. Neither kevplumb nor Agile is an idiot, not by a long chalk.
2. It's pointless to compare the use of plastic in u/f heating with its use in other wet systems. This is because (a) the temperature used u/f is different (i.e. less) than that of water when circulating through radiators, and (b) the risk arising from a burst is different.
3. You won't get anywhere by challenging (aka daring) other members to produce statistics.
Please don't confuse me with someone who's against the use of plastic - far from it. I'm keen to use it when it's the right thing to use, and the same goes for copper, iron, threaded, soldered, leaded, unleaded, compression, manipulative, and pushfit.