All my DIY life i've talked myself out of using plastic pipe and/or speedfit joints where pipework isn't easily accessible.
So I was quite pissed off when the contents of our CH system were running down an inside wall recently.
Upon pulling up carpet and floorboards I found a small hole in the pipe and Googling since has suggested that this isn't uncommon.
Just thought i'd chuck that out there in case anyone has a plumbing job coming up, copper isn't the job for life i'd assumed.