I haven't read the entire thread (and no intention of going back and doing so) but my take is as follows:
1) Having a single computer is fine apart from certain circumstances (more below).
2) If your computer craps out on you,it is dive over IMHO. Time to make a safe ascent.
3) In extreme circumstances, it is possible to rely on a buddies computer but only if you make sure you are sticking closely together. Maintaining different depths will cause your nitrogen loadings to diverge and therefore your NDL's wont match. My first OW dive post qualification was on a shared computer (the car containing all the rented computers was held up at the ferry so didn't make it in time for the first dive). We shared but stayed close and dived conservatively (well within NDLS).
4) If you are on a challenging dive (deep or long) or on a series of dives (such as a LOB), then it might be worth bringing 2. It would have sucked going on a LOB (with 20-21 dives planned) and have to miss some because I hadn't got a working computer.
As Colliam says, my preference is a wrist computer - IMHO it is far easier to use and more likely to be checked there than a console one. Air integrated or SPG is a different decision - I like AI for the ease of checking my air.
1) Having a single computer is fine apart from certain circumstances (more below).
2) If your computer craps out on you,it is dive over IMHO. Time to make a safe ascent.
3) In extreme circumstances, it is possible to rely on a buddies computer but only if you make sure you are sticking closely together. Maintaining different depths will cause your nitrogen loadings to diverge and therefore your NDL's wont match. My first OW dive post qualification was on a shared computer (the car containing all the rented computers was held up at the ferry so didn't make it in time for the first dive). We shared but stayed close and dived conservatively (well within NDLS).
4) If you are on a challenging dive (deep or long) or on a series of dives (such as a LOB), then it might be worth bringing 2. It would have sucked going on a LOB (with 20-21 dives planned) and have to miss some because I hadn't got a working computer.
As Colliam says, my preference is a wrist computer - IMHO it is far easier to use and more likely to be checked there than a console one. Air integrated or SPG is a different decision - I like AI for the ease of checking my air.