Another new user here, but, like Qbit above, I thought I should post my method, as much for another data point as anything.
I use a Volcano, pulling two bags, one at 5.5, one at 6.5 (up to about 200C). My duff is about like vtac's on the first page, maybe a bit browner.
I've made quite a few batches of brownies with my duff, using oil or cannabutter made by several methods, and this is what I've settled on, so far. I use this recipe
http://baking.about.com/od/brownies/r/ultimate.htm , which makes a more fudge-like (rather than cake-like) brownie. I think brownies made with butter are better than those made with oil, so I make cannabutter with my duff.
I've tried a few ways of making cannabutter, and I've settled on this, mostly because it's quick. I haven't been able to tell much difference between using this method, and, say, the water and butter boiling method where you must refrigerate the resulting mixture to separate the butter out. Since you can use this method's butter immediately, you don't have to plan a day ahead to make your brownies.
Like Qbit, I use a saucepan and candy thermometer, and simmer the butter (1/2 lb for the recipe + about 2 tbsp for "waste") with 12g of well ground (but not flour-like) duff at about 110C for 25-30 minutes. The lower temperature keeps the butter from burning (it becomes clarified butter, or ghee) and, from what I've read and experienced, should be a high enough temperature to allow all of the goodies to bond to the fat molecules.
I strain it through cheesecloth and a gold permanent coffee filter into a Pyrex measuring cup. You can squeeze most of it out through the cheesecloth, but inevitably there's some loss, and I end up with 1/2 cup of melted brownish butter, which has that vaped-remains smell. Since the first step in the recipe is to melt the butter and chocolate together, I only need to dump it in a saucepan and add the chocolate for a few minutes.
I cut the resulting brownies into 15 doses. Most people find one plenty, and two sometimes can couchlock me (a daily vapornaut). I find that most of the duff-taste is "baked out". The brownies, judged just as brownies, taste pretty darn good.
I'm thinking of changing to a double boiler so I don't have to watch the temp. The method of boiling the water & butter together achieves the same thing, using the water to regulate the temperature. I wonder, though, if boiling it in the water may have the added benefit of bonding any hydrophyllic inactive substances that you wouldn't want in the result anyway to the water, which is then drained off. I may try that method again, just to see if it improves the taste (not that it needs much), if not effectiveness.