A lot harder, if you have a necklaced BO second stage that gets in the way. So I guess I could just bungee my BO second stage to my tank (some DSV divers do that, even for their deep bailout). But that sounds like adding more stuff to do during a period of relative incapacitation.
From what I understand (not from personal experience) skills that are trivially easy in training can become next to impossible during a CO2 hit. Which would be one of the reasons for bailing out.
From talking to my really deep diver buddy, he points out that he doesn't put a BO reg around his neck for several reasons. One, once you are carrying multiple cylinders, you need to switch to the correct one. Your bottom BO gas could possibly be hypoxic at a point you need to bail out shallower, for example, so just having one BO reg/gas for all situations is not an option. And, two, the training includes switching BO cylinders with your buddy once the person on BO breathes theirs down to half. Swapping doesn't work so well if the reg is around somebody's neck. The skill done in training is the same for all BO cylinders and does not include dealing with a BO reg hose that is around anyone's neck. And, as he says, "if you don't/can't drill on it, then you don't do it during a dive."
His training - and mine - included drilling to be able to deploy the OC reg from where it is stashed on the BO bottle very quickly. I will say that his training does also include having a BOV (on his X - his JJ training did not include having a BOV).
I do realize everyone's training is not the same and I'm not trying to say any one way is better than any other way. I'm just trying to discuss the different approaches, to help ME understand them better.
One thing that seems like it might be relevant is, if you're having a CO2 hit, you CAN stay on the loop for another second (or two or three) if you need to (I think), in order to switch to BO. And if your reason for switching to BO is something else, you probably aren't having the same mental or physical issues, such that pausing your breathing for a moment, if necessary, while you deploy and switch to a BO reg is a major problem. Which means, what I'm trying to say is that I'm not sure the time it takes to deploy a BO from a slung cylinder, versus switching to one on a bungee necklace is a "real" issue. Is it? I don't know. Maybe if you got really unlucky and just sucked a big mouthful of caustic, it could be a problem?
This is sort of OT from gag straps, but all of this is really making me lean more and more towards wanting to have a BOV. I know some people say that they are not needed and you should always detect an oncoming CO2 hit well enough in advance to be able to switch to BO without needing a BOV. But, is there really a downside? I mean, if you ARE able to detect the CO2 building up, you don't have to use the BO, right? You could have it and still dive as if it's not there.