To use a back up SPG or not?

[Thalassamania]

Wireless has two advantages: all the information on your wrist in one place and knowing your buddy's tank pressure. Is that worth it? I'm not sure, except when I'm diving with kids, then it's worth it.

 

[Rascally Rabbit]

Hoseless gauges IMO expensive gagets that have no real world benefits. In close in places where less hose means less chance of entanglment, most divers use a SPG for backup I've used the same SPG now for 25? years. NEVER failed that is NEVER failed. When hoseless can make that claim then maybe I'd consider spending that kind of money. Keep It Simple Stupid KISS a concept to live by especially when diving.

The problem is that because of the way SPGs fail you will may likely never know that in fact your SPG is in a state of failure. Reading higher or lower than actual pressure beyond acceptable variation.
So the real fact is that your SPG can't make the claim that you are requiring of the AI computer. The way that a AI wireless fails makes you aware of it's failure unlike the SPG. Personally I'd rather be aware than have the posibility of being surprised by a functional yet inaccurate SPG reading higher than actual pressure causing an OOA incident at the end of a dive.
It is possible for a SPG to read 500 psi and have an actual tank pressure of 200 psi at this pressure a first stage may shut down and for all intents you are OOA. This SPG may still read Zero and Full pressure properly.