Question What is your tolerance for error in your SPG?

[OTF]

Worse than inaccuracy is sticking. It's hard to replicate so I'm not sure, maybe I'm crazy, but I believe I've had analog gauges "stick" for a while at some pressure, then start working again and suddenly drop to the correct pressure.

 

[Belzelbub]

Add to that the advantages of being able to see at a glance that the relative angle of the needle is where I expect it to be without even registering what the number is

While not exactly a needle, there is a graphical representation of tank pressure on the Perdix. Just above 2056 in the picture I posted, there is a tank icon. The colored bars indicate how full it is compared to working pressure. Working pressure needs to be set manually in the computer. Probably not as easy to see at a glance as a needle, but it’s there.

I use both AI and an SPG at times. I find that even though the needle indicates the relative fullness of the tank, my brain wants to put it in numerical form, so the numbers on an AI computer is faster for me.

Worse than inaccuracy is sticking. It's hard to replicate so I'm not sure, maybe I'm crazy, but I believe I've had analog gauges "stick" for a while at some pressure, then start working again and suddenly drop to the correct pressure.

Yep. I’ve had this happen. it stuck at just under 3000 psi. I knew that couldn’t be right given the time in the dive so far. I flicked it a few times and eventually it stared working again. Had it stuck at a lower pressure, I might not have realized it was lying to me at first.