For what it’s worth, I have used a 15 ohm resistor, in my version 1 Budaschnozzle at 24v, with good results, (single resister), a 12 ohm -may- work, but be sure to put epoxy around the resistor, to transfer the heat to the block, or it will burn out. I use J B Weld epoxy, because it can take the heat. So far, I prefer 2 heater resistors, for the faster heatup. My experimental heater block, as shown, is wrapped in ceramic tape, and then kapton tape. This picture is from before the hot end was wired in. I used the lulzbot wiring parts, as provided. A custom aluminum block was substituted, using the same methods as lulzbot (setscrew). I may not need all the heat I am getting, but it seems to work well, fast heatup, seems to print fine.
Pic at: http://botzone.ca of modded heater, with new aluminum block, and two 15 ohm resisters, in parallel, at 24v.
The firmware I use is Marlin, and the machine, is a prusa mendel.
I love my Budaschnozzle, it works really well. I cool the upper part with a small fan, to prevent jamming, from the heat getting too high in the head. I also, always back out the filament before shutting down. I hope to get a chance to try out a v2 hot end soon.
Sorry, my site is very much under construction at this time.