Whilst it is easy to jump on the band wagon and agree with you, maybe some clarity would be useful
What age is a 'kid' for example? I am assuming that you don't mean anyone under the age of 18?
What is 'preying on'? Are we talking about sexual assaults only? I know of someone who was accused of kidnapping a child from a school (and it was covered in the local papers as a paedophile style attack). In fact it wasn't, it was actually the chaps daughter who the mother was refusing to let him see.
I am also assuming that 'proper' justice is done and there are the proper appeals procedures.
There is an interesting study here:
http://www.homeoffice.gov.uk/rds/pdfs/r144.pdf
According to this research (and not wild ass guesses / Tabloid sensationalism) there is a good proportion of paedophiles who respond to treatment and do not reconvict.
That said there is still the risk of attacks and scarring innocent children.
Personally, I think I would accept the death penalty for convicted paedophiles
in the high / medium-high categories.