I'm not only concerned about the potency, but also concerned about the health issues that may present themselves when different modes of extraction is used. Like I've heard that BHO is great as far as potency goes, but is not the healthiest thing to suck into your lungs. Don't know if this is true or not.
Okay, a quick and dirty on concentrates. Well, maybe not so quick.
When done correctly, the extraction methods, BHO vs C02 etc, affect mostly price, taste, and consistency. You'll find C02's to be slightly less potent (marginal difference, I've read an average of 10%), of a better flavor profile, and a great consistency for the harder to load vape pens. It's generally thought of in a more positive light than butane extraction since it's safer to work with, but they are more expensive.
BHO gets a bad rap because people have literally died; explosions in home extraction labs and the like. Barring that, in terms of potency, it's the better of the two in most cases. You find a lot of different consistencies (runny oil, shatter, wax, budder, honeycomb, taffy, crumble) which give you a lot of options in case the VIP needs a certain kind. If not, the differences in consistency only have to do with ending steps of extraction. For example, budder is just wax that's whipped when warm for an airy finished product. Taste will always have to do with your starting product, but, in the case of BHO, can be greatly influenced by how much remaining butane is in the extract, it can taste disgusting if not purged well.
It is important that both be purged of the solvents used to extract (especially at 55/G, that should be given), so always ask how it was purged (usually vac) and shoot for the most well purged you can find.
Health wise I read C02 is safer than Butane, but the amounts of butane you'll find in even the most badly purged BHO would not likely be at toxic levels. Here's a link and some commentary on the subject from OF:
The stuff is just not that dangerous:
"This product is considered to be non-toxic by inhalation. Inhalation of concentrations of about 10,000
ppm may cause central nervous system depression such as dizziness, drowsiness, headache, and
similar narcotic symptoms, but no long-term effects."
http://www.hovensa.com/pdf/butane.pdf
Note that 8 hours exposure to 1/10 of the intoxicating level is allowed. It's considered OK to live and work around it, breathing it normally, without ill effect.
OF
After that, I'd say what you want to look for are lighter oils, your blondes, light greens to green-yellows. These are usually the most pungent as well, but there are outliers to this test. Try to find oils with as little particulates (left over plant matter) as possible; I'm guessing the VIP runs with a heat coil, and those can gunk up real fast from wax with tiny amounts of plant matter. This is also important for those who use nails for concentrate, the more particulates, the more residue left on the heating surface, which calculates to a pain in the ass.
Hope you enjoy your new vape pen and welcome to the world of wax.
I'd also like to have something really small and stealthy for day trips, where I don't have to haul herb/vaporizer, or have to rely on the PowerUp capsules that I currently use -- actually, I want to find an exact or better substitute for them, and I suspect that concentrates are the answer. I need 3 capsules to get me through a work day. That's $5, plus my edibles & vaping when I get home. I really think that concentrates will save me some cash.
Maybe you should try an alcohol tincture like Green Dragon, or, if you like pills, you might like some of BadKitty's methods of on GrassCity. She does some great canna-capsules with kief / hash.
Good luck with your VIP's. If you like the style of these pens but aren't very happy with performance, a comparable (maybe better) entry level pen like this is the Vapor Brothers Dabber. After that, check out the Omicron / Persei, or the Revolution / Cera.