It's definitely possible to get a good vape and experience with changa/ehanced leaf in the gvg with dedication and the right technique, but even then if you smoke the leftovers in a regular pipe you will see that you only got a fraction of the love that was in the mix. As always, this is only my personal experience and your mileage may vary, but I'm 100% convinced that changa/enhanced leaf (harmalas or no) are best combusted and the gvg is best for freebase.

I have yet to make the plunge of trying changa in my electric vaporizer but I suspect it will probably work quite a lot better than the gvg since you can control the temperature and find that sweet spot. Freebase harmalas put off a tiny bit of vapor right at 400-420 degrees fahrenheit then just cinge and turn black in the electric vaporizer, they do basically the same thing in the GVG. So I suspect right around 400 F is where you will want to vape a changa blend in an electric vape. I think this route definitely needs more looking into.