Other buyers don't seem to have had any issues, and vendor is communicative fortunately, so far.
And yes, you can vaporize mephedrone in a meth pipe. It may burn easily (unless you have a lot of practjce), but if you get it right it hits hard - although snorting/swallowing mephedrone in my experience is the best way to experience it by far.
Snorted: 200mg (no effect)
Pipe: 50mg at one time (maybe minimal stimulation)
contacted vendor