well i have smoked weed, and the following jwh's: 018, 081, 250, 200, 073 and i've mixed them in every way possible. I am not really able to analyse my highs as much as some people seem to, high is high, but here are a few thoughts.
weed: all i mostly ever get is brick weed, sometimes just okay, but lately been getting some that is surprisingly good. on one occasion i did get my hands on some locally grown, the main difference was the local grown stuff was so moist, and smooth to smoke, good stuff. also got a coupe pulls off a joint of organically grown weed from cali that was excellent. weed is always good to me, never get paranoia, relaxing, happy, mildly trippy. love it.
jwh-018. i get a mine from someone, who ads it to the plant base for me, so can't comment on the dose, although anything over 4mg seems like a mistake to me since this stuff can be very unpleasant if you over do it. but when you get the dose right it is pretty good. missing some of the happyness i get from weed, but much more trippy. lasts for about 1 hour, and then another hour of fade. strongest one i have tried, do not over do this, and eyeballing seems like a huge mistake to me, i did it once and would never do it again.
jwh-073: much milder, much less potent, anywhere from 9-12mg is a good dose, this is one that i will occasionally eyeball, because it has alot more room for error, can be a bit trippy, but no paranoia, last about 30 min for me, with an hour of fade. if i've smoked weed in the last couple of days i can't get anything from this one.
as far as mixing them, i've never been able to notice a huge difference, the stronger one usually overpowers the weaker one, but then i've never been one who was really able to super analyze my highs.
jhw-250: this is a strong one, nearly as strong as 018 4-5mg is a good dose, strong trippyness that lasts for 30 minutes, and then about an hour fade, the hour after the main high is still pretty good though, this one has more of the happy relaxed feelings that 018 is missing. this one is pretty good.
jwh - 081: the high from this one is medium strength, no paranoia, very relaxed and happy, the main high last for 30 minutes and then 1-2 hours of fade that is still pretty good. smoking too much of this one makes my body feel like it is pulsing in an uncomfortable way, and taking this one orally and mixing with alcohol is not good, racing heart rate shaking, stick to smoking it. other than that this one is pretty good. 5-6mg is a good dose.
jwh - 200: this one is very weak, in fact i have never really gotten high from it, just mild relaxation, gave up at a 12mg dose. i would skip this one, plus it seems to weigh less, so 12mg is actually a decent amount of material, and don't care to smoke this much of a chemical