I have always worn my deep bailout second stage necklaced, despite having a BOV.
This has several positive attributes incl. making it easy to switch to if the BOV is compromised for example by caustic fluid, deep tank ID is easy to correct before the dive and less risk of damage or pinning by a tank on top of it.
That said it does inc. clutter in the already busy chest/throat area, it's easy to catch it and induce a purge either on the boat or while reaching/accessing other gear, and very difficult to hand off if ever required.
I am relatively comfortable that the switch and ID issue can be trained for so the main reason for having it is as an emergency bail out if the BOV failed or was full of caustic.
I test the BOV on every dive so the latter is more likely, but what sort of incidence level does this have.
I know it has happened to Barry and I think also to Mark and it crops up fairly frequently on RBW but mainly in aged threads so wondering if the incidence level has decreased with better awareness and preparation.