A reset on the boat, right before I'm about to splash, and now I need to re-setup all my settings is not nearly as convenient as picking a time when I'm not diving for a week and sending a Teric off for a new battery.
I understood that.
You are not the first person I have read about that was getting a cylinder pressure reading before they splashed and then stopped getting one after they splashed.
Your reason may be different, but that just tells me that there are multiple ways it could "not work" - and you can't tell with any of them until you splash.
I have been using AI for almost 10 years and do not use an SPG. I think it is a negative to have both. But, I concede that if I couldn't tell if my AI was going to be working after I splashed, I might have an SPG in addition.
Shearwater computers also tell you if their transmitter battery is getting low. Generally, you have plenty of battery left at that point to do a day's diving and then change the battery that evening. For whatever reason, however, they do not tell you any other battery status. You cannot, for example, check and see that the transmitter battery is at 50%. They only show a Low Battery warning when the transmitter battery is getting low and that is it.