For this application I personally prefer an analog gauge. There are too many parts and human bits and pieces flopping around in loose formation to get a perfectly stable cracking pressure. Thus, the needle wavers around a bit, but your eyes are good at interpolation. For HP and IP, though, I prefer digital and use Dwyer gauges.
If you have a test bench with a stable adjustable vacuum source, digital might be good, but to me that seems like overkill unless you rebuild regs for a living or manufacture them.