Push to connect vacuum fittings

I see push to connect, sometimes called push lock pneumatic fittings with nylon hose are becoming popular these days. However, I have some reservations about using them on a wastegate(s). As far as I can tell, the all metal fittings are only good for 240° F, that seems a bit too low for a wastegate fitting. I've still seen them used there regardless. Does anyone in here have any experience with these fittings? Thanks guys.

Heat is a definite consideration, however the amount of heat the wastegate lines are exposed to is dependent on the layout in the engine bay and it's possible to use the pneumatic hose fittings in many installations with good results. Care however is definitely required. I'm not personally a fan of them and prefer to use AN fittings with teflon braid if I want something a step up from silicon hose.