In any case, I'm in the bandwagon now. I designed an Arduinix(TM) variant, based on my previous observations. One of the main differences is that the components sit low on the board, so that a "tube shield" can be plugged on top, similar to akafugu's VFD modular clock. The top "tube shield" can host (at least in theory) up to six IN-2 or four IN-17 (four IN-12 would not fit).
Lesson learned: don't design the PCB until you have all parts in hand.
PS Getting the high voltage (180V) on the new board was just a matter of adjusting the trim pot. No surprises this time.
PS2 Although I did not try it yet, the "Open source Nixie tube shield" sketch should work, with minor modifications, with Arduinix, I reckon.
PS3 Please contact me if you have a need for this PCB or want to buy one.