Marie, if I may I have some suggestions... IIRC, you're not doing any penetration overhead diving, right? I would really consider the streamlined open water setup. You mentioned you bought a necklace for your octo but doing that the way you currently have your rig configured could lead to some confusion. When you necklace your octo you donate your primary second stage. If you use that yellow hose on your necklaced octo then you're creating confusion to an OOG diver.
Sorry I disagree.
In teh Tec diving world (and teh world of SB) this may be what people practise. But not everyone does.
I personally Have my Alt 2nd on a necklace It's also on a 40" hose with a 90 swivel routed under the left arm. My primary is the same but routes under the right arm
I brief either primary or secondary donate depending on what my buddy has been taught. There is never any confusion.
Last year I was examined on a course with 2 instructors (obviously attempting to win Oscars for acting) having to carry out OOA donations and air sharing at depth (20m) and ascending to the surface.
Not once did they have an issue with my rig, and it worked. It didn't matter if I donated or if they snatched (to try to catch me off guard) it all worked. There is no "wrong reg" i.e. one too short.
Now I'm not saying my way is the right way, it's an alternative.
If you are diving as team, with everyone practised in drills, then yes you use that method. However because I dive with buddies of mixed training agencies, and often guide people of mixed abilities, I like to have a rig that has more than one option for a panicked unpredictable OOA diver.
Interesting you prefer a second inflator for you dive alert and lift bag inflating, While I find my alert is okay on my wing inflator hose and use a reg for lift bags and dsmb - horses for courses right?