One point about the oven temp is that air is a very poor conductor of heat. For example, you can stick your bare hand into a 325f oven & you won't get burned. Sticking your hand into a pot of boiling (212f) water is a whole nother matter.

A 325 oven will take a while to (over)heat the plant matter to 325 degrees. Hence the 5 minutes.

Decarbing in the oven seems to work fine for me, but the very low temp vape sounds interesting. Shame to waste all those tasty terps.

Oh one other point - things do start to vaporize before they reach their boiling point. Steam is coming off water well before it boils, after all. If anyone has a clearer understanding of phase change physics, I'd be interested to hear it.