Here is my take
When you start getting into big dives the number of failure points goes up and up, not uncommon to get stuck last minute having to change an o-ring out or swap a reg or something because out of the 4+ regs your taking one has a malfunction or an o-ring isn't seating or your primary isn't striking or a backup flooded on your last dive yadda yadda you get the drift
All of these things slow down the time it takes to get in the water and do your dive
I've dove with guys with wireless and several times it caused serious delays in getting into the water - is it because wireless is evil and will kill you? no, but its another thing that can go wacko on top of everything else.
I've stood in little river basin for 30 minutes waiting on my buddy to come down, he never did, wireless problems, this did not contribute to my fun it sucked
Too many times I've screwed around on the surface helping a buddy turn regs on and off while he fiddled with a computer, very annoying
one time too many I had a buddy bolt in the middle of a dive because he couldn't read his pressure and decided "he had to get the hell out of there" don't care to elaborate but it wasn't a cool situation
I know of one case where a buddy team got seperated, wireless problems popped up so that the survivor didn't know how much pressure he had to search for his buddy, he made it out his buddy didn't (note I don't blame the wireless for the death or the buddy, even with an spg the outcome may have been the same but... with an SPG there would have been no doubt about remaining pressure)
My attitude now is, if I see a wireless transmitter and no SPG, I'm not inclined to ask that person to dive with me.
Wireless on rec dives, sure, one less hose etc its a cool feature
technical dives.... well like I said, if I see a transmitter and no spg thats not a dive I really want to be on, I hate the things, another "toy" to screw up that is a fix for nothing - if its not needed don't take it, stick to SPG, you don't have to worry about its battery dieing, flooding, or not talking to your computer.