Deeper and longer chews through gas with bailout being the main bottom time constraint. Yes, there's the shot line with other divers gas, but "what if" the bailout meant loosing the shot too?
Just prudence really.
If you do need bailout the important check is that the gauge doesn't show gas when it is actually empty. After all, unless you've been very unlucky, when the gauge says you've run out the surface shouldn't be far away. Possibly bent is better than drowning, and possibly bent is usually not bent, and even a bit bent is usually repairable. Drowning tends to be a lot more binary.
Living life in the world of 'what if' is a terrible idea. It's like being trapped in a crazy movie where you are being forced to deal with your worst imaginings!
IMHO just enjoy the moment, be fairly sensible, deal with obvious stuff, and make the most of what you can see...
Regarding deco bailout regulators (not the deep bailout)... What's the opinion of putting an inline shutoff valve on the reg (with an OPV on the 1st stage)? This means the 1st stage can be left powered up (therefore dry), but the 2nd stage wouldn't be able to leak gas if scootering or the reg gets knocked.
Had a leaking XTX50 2nd stage which lost about 50 bar of deco gas last weekend. Annoying, but still plenty of bailout.
Or should the first stage always be dunked - cap off - into fresh water and flushed through by connecting the stage to a cylinder and purging?
A month ago went to a diving lake to check out a new drysuit and undersuit for leaks, weighting, etc. In sidemount as them's the rules for solo.
About 5 mins in the necklaced XTX50 regulator went into an uncontrolled freeflow -- amazing how much gas comes out and how much it buffets your head! Shutdown the valve, tried again after a few seconds and it freeflowed again.
The sidemount regs (2x Mk25 with XTX50) were recently serviced. Checked the IP which was fine. Didn't freeflow again later though, nor in a pool check.
I'm really getting tired of some of these problems. My kit's pretty much all Apeks and have had several second stage issues even with ATX40s. Pissed off about the Tec3 body which they want the price of a new reg.
Also pissed off with Apeks cylinder valves which are most definitely not "the best". They're pretty shit as they are tight to open, open really suddenly, not good for oxygen. But worst of all I've had several where the valve leaks when the knob's pushed around (e.g. carrying). For bailout it's not good.
Given the opportunity I'd change them all to another manufacturer.
Caliph Hamish Aw-Michty Ay-Ya-Bastard, Spiritual leader of Scottish State in England