For me, what you seem to miss here is we are not talking about equipment that has high failure rates to begin with. Computers and transmitters are quite reliable in 2019. I have actually had 2 SPG related failures but zero issues with computers and transmitters.I can play the same game you are, I did not make an accusation , By saying """""" think"""""" it becomes my opinion. and you also just did the same thing by so called attacking the person and not the merits of the opinion. That does not forward any conversation to being more productive. The merits of more complicated means more prone to failure should be an accepted concept. to replace a complicated process with an equal or more complicated method as a backup should raise questions regarding the soundness of the decision to do so. Also as I said before If you look at the DIR process it is completely 180 in regards to the idea of using a computer as a replacement for another computer when a simpler method less prone to failure exists. Their thought would be use the simplest, time proven lowest failure rate method as the primary process. So please re read my comments with that aspect in mind. These discussions should be able to conducted with out those that do not like your message to nit pick words or spelling or punctuation as if it has bearing to the message.
So again I will say that although I am not a strict DIR company man I agree with their view of the concept of simplicity being the best and to deviate you have the unavoidable chance to take on failure you are not equipped to handle.
We are also talking about recreational NDL diving here, so in the incredibly unlikely scenario that both of my computers and transmitters were to fail, I'd just end the dive and ascend. As I'm more likely to win the lottery, in the meantime I can dive with higher confidence of not having to ever end a dive early or sit out a day of diving due to an SPG, computer or transmitter failure.
Therefore, I don't see how that is adding any real complexity to my equipment and I'm certainly not taking on any extra failure modes that I'm not prepared to handle - in fact, I'm better prepared in the event of a failure in my opinion. A transmitter or computer failure on a trip would be pretty much a non-event given the redundancy.