@ dhenry...
This is what I got:
3.8v / 61.2ma
7.6v / 61.4ma
11.8v/ 61.6ma
That must be one phenominimal transistor you tested? with... to vary 400 uA Ic over a 3 to 1 load range...
thats .0004/.062 = .645%... or is it bad data...
Because it is Much better than Many Commercial CC drivers.
The Data posted by Erni is good and fairly representative of a high beta transistor driven within it's limits however yours is an order of magnitude better.
I think you are on to something there with great commercial promise.
Or you are just "On" something which seems more likely.
Bob