Sorry to leave you all hanging, poker night last night.
Yes you will still lose some terpenes if you decarb the hash, but if you quick dry your buds in the oven they tend to keep that grassy hay smell/flavor because the chlorophyll hasn't broken down like it does in cured buds. That's part of the reason we cure our buds. If you really want to keep the terpenes (and yes they potentiate in food as well as smoking), fresh washed buds and a natural decarb tincture are the way to go. But that defeats your purpose for quick harvest to product. Dr. Ethan Russo has an interesting paper,
Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects.
Thank you for jumping in with the decarb data, I never went into detail as to why Im using this time/temperature. Though I have to say, I have seen your numbers floating around a lot more lately. I used to be a 220°F for 20 minutes guy (BadKittySmiles), but your data along with my own bioassay proves that 240°F for 40 min is much better.
8oz / ounce should cover the material, but you should multiply everything though, so use 12 fluid oz. for each rinse. Otherwise the efficiency number (0.75) will be lower. I think the number is around 0.60 for a single rinse, but don't remember exactly. You probably will still get a fine tincture (single rinse is usually lighter in color), and you can always save the material for a "depletion batch", which I will demonstrate some time next week I hope. As far as reducing, that's a personal preference and if you get it where one dropper is a good dose, all my recipes will come out with that potency (unless it's noted as a double or triple batch).