Unfortunately I don't have scientific metrics to support any of this, but based on my own personal experience I am in complete agreement with bufoman. I've weighed out specific quantities of aborts to match the equivalent of a single, potent, mature specimen of the same strain, from the same flush. I definitely have never gotten the same potency per weight from aborts as I have from a mature, closed cap specimen.
I too have heard many arguments that the aborts are more potent per weight, but my personal experience tells me otherwise. The best thing I've found to do with the aborts is to collect them all, dry them, and put a mass of them in a jar of honey. If you get a nice dense concentration of aborts to honey, then just a couple spoonfuls will treat you well. The honey also preserves the aborts, so you can save this concoction for a time when you are out of mature specimens... I've heard that honey (in some way) will potentiate the alks, but I honesty don't know if there is any truth to that.
I do like to be able to say: "This honey makes me feel funny" though! :d
Peace
-idt