if it was me id go new. As its a major component amd not a simple swap over if it goes, it wont cause a cambelt failure but just increased hassle
I never had my dephaser changed when i bought the car 2 years ago when birchdown did my belts, at the time they weren't talked about on here, but because of all the threads on here lately in my head i think i can hear it ticking even though its probably fine lol
If your like me once i get sonethings up in my head, itll eat me away and always be in the back of my mind if i put a used one
When its new you know itll last and be carefree
Thats what id do