A somewhat tenuous argument. While I don't dispute the advantages of havign a bright easy to read screen, in such a circumstance you do have the audible warnings to guide you. After all (for OC rec) you're not looking for the perfect ascent, rather than a safe one. Don't you agree?
I did my Rescue training in a low-viz quarry. My training was to get the victim and myself vertical, using my left hand to hold up their inflator, to dump gas during the ascent (possibly switching to my own, as well, as needed), and right hand reaching around to hold the reg in their mouth.
In that scenario, I could not see anything on my left arm at all. However, I could potentially see a computer on my right arm. However, I would not be able to press a button on it to turn on a backlight. Nor could I shine a light on it.
During the training, I could not see the bottom or any other visual reference points. I don't dive with a computer that gives audible alerts, nor would I be likely to ever try to use audible alerts as a way to control my ascent.
Because of the viz where I was, I could not even tell if I was ascending or descending - except by looking at my computer.
Thus, to ME, because I want to be prepared for the possibility of an emergency even during my somewhat-common diving environment of very low viz I feel like it is important for me to have a computer (even during Recreational dives) that is easy to read in low visibility, without having to press a button or shine a light on it.
"Tenuous"? Call it what you will. I think it is perfectly reasonable to plan and make purchases based on being prepared for emergencies, even if it's likely that you will NEVER encounter such an emergency in your actual diving. It's the same reason I carry an SMB and reel on every dive. I've never yet been blown off a wreck, but it could happen and I want to be prepared in case it does. Same reason I have an octo. I've never run out of gas nor had to donate to anyone else. But, it could happen.
