What do you mean with the formaldehyde thing?:
1_Is there an increase risk for people who vape in combination with the spice?
or
2_ are you talking about the current risk that every single vaper in exposed when using PG VG e-juice?
My stand on the e-juice has been this one: I only take it ocassionaly (with the spice), I am no vaper. I hope that if all those millons people around the world haven´t die yet, this liquid can´t be so bad. I know what they say... it could take years for symptons to appear, it´s not like cigarretes, which have been around for many years and we are fully aware of its effects on people´s health.
Regarding your inquiry, what I can tell you from my experience is that a mixed VG-PG juice with no nicotine (according to ducdevil post where hyperspace entities manifested their dislike) will work (not even 100% PG). I use 1:6 ratio (slow intake, 2-4 hits) but I´m willing to try 1:5 next time (more experienced users would preffer 1 hit ratios).
Also, get one of the big devices, not the thin ones ("pen style", cigarette like). With a sub ohm atomizer. (I have a "vaporesso mini" and worked really well at 35W, don´t remember the exact atomizer though, it came with the kit). Try to practice making big clouds with the e-juice you´ll use to mix the spice into.
Also, this method doesn´t allow you to easily combine the harmalas with the spice, I recommend you not to forget about the harmalas, spice only trips can be a little bit alien...
You can check and infographic I made here:
E-vape infographicPlease, report on your experience with the E-juice, I´d like to get more feedback, specially on the E-juice preparation and limitations.
Good luck.
"...after five seconds I was no longer a marxist, no longer a materialist, no longer a rationalist.
It killed those things, it cauterized them..."Terrence McKenna