I've done both the alcohol and butane extraction methods. If you don't like the green syrup that the alcohol presents (and who does?) butane is your solvent. The green is clorophyl (so I can't spell -- so what?) and other gaggy stuff. I've separated the green out of alcohol extractions, but it's messy, stains everything, and tastes more like the tar you scrape from your pipe when times are hard than essential oil.
On the other hand, The butane extract is a cheery gold color from the get-go. Butane doesn't seem to pick up the green much at all, and the post-extraction separation of the desired goodness and whatever else the butane leeched out is done quite simply with reagent alcohol. The good stuff is carried in the alcohol, and the rest beads up on the bottom of the container.
I use the same apparatus I described above to re-distill cheap vodka. Two passes thru the still (first pass at 190f, 2nd pass at 175f) and the resulting moonshine won't float a hydrometer at all, so I don't know exactly how pure it gets. It burns bluer and hotter than everclear though, and evaporates more quickly too. I use this stuff for post-extraction processing with good results. I've tasted it too -- pretty nasty, but a spoonful will give you about the same buzz as a black russian . . .
If you folks like cooking with this stuff, the butane extracted product is almost impossible to taste in anything I've added it to. Budder tastes like herb butter. Brownies taste like brownies. I don't advocate ambushing people with laced brownies, but it's certainly that undetectable. I can't say that about the alcohol extracted oils, or about the kiff/powder hash products.
Think analog ~~ Act digital