There's just no need to ramp up the temp that close to combustion. There's plenty of room in the 400's for high temp vapor without going up close to 450. I'd rather avoid smoke in a vape and just burn one if you have to push the line between vapor and smoke.
I think we all agree combustion is not a goal here, that is you shouldn't be doing it. Yes, you should be keeping control of the temperature. But that's not how I read the original question. I see it as more 'can all vape pens potentially combust'. Can they, not will they if not controlled properly. Or is it self limiting (safe).
Guys want to avoid accidents, it can harsh yer mellow for sure..........
I think it's fair to say some just can't get that hot, but they tend to be pretty useless. Open loop (uncontrolled) pen vapes I think are risky if they're useful. The possible exception would be the TV Evolution, now out of production. Being true convection you have to work very very hard to make it combust it's not going to happen because you get loaded and stop paying attention or because you hand it to someone who hands it to some fool nobody knows like the others.
It's just too small in scale to do open loop I think. The numbers are just wrong. It's going to have to be physically bigger and approach it differently to work. MFLB is a good example. As is it's clone/repackage, Palm. For a few more dollars you can go with flashvape if you're basically fearless. With care, I believe you can rig it to be pretty much combustion free. It's like a MFLB on steroids. With some fun options. It's not for the timid IMO, not a 'sipper' kind of vape. In that same $150 or so you can get a Solo and have a serious closed loop rig (where you set the temperature) that allows you to set temperature within small steps and is basically all glass for the ultimate in taste. If stealth is not a major factor, it's very recommended as an alternative.
By the time you've bought a couple cheap pen vapes you could have been enjoying a purpose built, high quality, trouble free (for the most part) vape instead. Given the value of herb you hope to run through it and how long you hope to enjoy it, IMO this is a time to consider other options that won't be combusting unexpectedly (or at all) and won't need replacement before summer sets in.
Regards,
OF