fractal fountain, i have tried 081 alone and in combination with 018.
if 018 is mainly medicinal or body stone, then 081 feels the opposite, very heady high. they combine incredibly well orally. 3mg+3mg gives a very intense stone if dissolved properly in oil. 5mg+5mg is enough to put a non-tolerant person down for a nap. 10mg+10mg gets tolerant cannabis consumers into a very nice high.
imo, oral JWH combos can be nearly indistinguishable from the real thing, other than the odorless brownies.
edit: forgot to mention that my experience may be colored by what i've read... i believe 018 is selective for CB2 mainly, while 081 is selective for CB1.