Pete, the OP asked a question. I answered it.
If you'd like a more definitive answer, particular to the Tec40/45 course..... and the PADI TecRec approach, here it is...
TecRec Tec Deep Diver Manual, page 38:
"SPG (Submersible Pressure Gauge). You only have one of these because two creates the potential for two high pressure leaks. If your SPG fails, you'll end the dive immediately anyway....The preferred SPG is the simple, mechanical type because it's reliable (no battery concerns). Few tech divers use air integrated computers, whether with hose or hoseless. They're electronic, tend to be bulkier, and if the gauge fails, you're out of two, rather than one instrument".
Not my words. Not my opinions.
The OP asked about Tec40/45.
He didn't ask for random opinions or some rant on civil (diving) liberties. He wanted advice for his upcoming training. Am I 'big headed'? No... I teach Tec40/45 (and 50...and 65...and Trimix). It's my profession, not a hobby, and has been for a decade.... so forgive me for being sure of the course specifics.
There's no authority for tech diving, but it's not a consequence-less free-for-all either. Simply READ THE THREAD... the question was about tech TRAINING... and there is authority on that.
What I've attempted to do was provoke thinking on the wider issue... Tec principles. These also are clearly worded in the Tech Deep Diver Manual... and pertinent considerations for the OP at this stage.
TecRec Tec Deep Diver Manual, page 192:
"The Principle of Procedure and Discipline. You follow the rules and work the procedures without exception on every dive, no matter how familiar the dive and no matter how much experience you have. To state this in a negative context: Cutting corners kills".
Thats not 'DIR'.... that's PADI...
Pete, you can object all you wish. The fact, I don't log into Scubaboard to engage in a battle of egos,.... I enjoy teaching and I e joy helping people. That's my aim in this thread... to help the OP. To provide accurate information and promote beneficial mindset development for his future tech training. What's your aim?