Hi:
I'm inclining toward making some future Nixie clock designs follow this pattern, mainly to conserve the big expensive tubes.
I'd prefer if the size ratio could be kept to about 1:0.66, but I think I'll have to settle for 2:1, such as 30mm digits for HH:MM and 15mm digits for SS.
Who prefers all the same size digits?
Who prefers smaller seconds?
Who doesn't care as long as it has numbers glowing orange?