My current thinking is go with one solution to an OOA situation and train until utilizing that solution becomes reflexive. I'm leaning toward the gas planning and buddy solution rather than a pony, since 95% of the time I dive with the same, reliable buddy--my wife."
That is how I see it too. However in my case using the same pony system is more knowable, reliable and controllable than the many different buddies and equipment configurations I encounter. While I
completely respect your choice, choosing the buddies gas comes with many unknowns for
most divers:
Unknown buddy
Unknown buddy response
Unknown equipment configuration
Unknown maintenance
Unknown distance from source when event occurs
Unknown amount of gas when event occurs
Some (like you) may counter that they only dive with known buddies/configurations to alleviate those unknowns (which is a perfectly valid strategy) but I would say that this pathway isn't that liberating - in fact it can be, in some cases (as when like minded divers are not present) severely self limiting.
It also limits (in ordinary circumstances) equipment choices and the variety of people you can dive with. After all, you can only dive with people who meet those criterion, when they are available, and want to do the same dives you want to do. I would question whether recreational diving warrants that degree of confinement.
Now look at a pony:
Regardless of buddy or configuration:
Known equipment
Known maintenance
Known response (muscle memory)
Known distance from source when event occurs
Known amount of gas when event occurs
To me, these are the keys to a dependable bailout strategy. Close to the diver, known to the diver, controlled by the diver. One may (should) depend on strong buddy/team skills for the ordinary operational nature of a dive but emergency bailout doesn't also have to be dependent on this approach.
I would say that in a known, trusted buddy team, using their gas for bailout is viable, but even in the best of circumstances there is still an unknown element; primarily the distance between divers when an event occurs. Unless you tie a rope to each other this cannot be said to be a given.
The objection that someone might see a dive as being benign enough to leave the pony behind is as valid as someone seeing a dive as being benign enough to compromise on the "known buddy/configuration" strategy. Both are possible.
As a vacation diver, what would happen if your primary buddy got sick at the start of the holiday. Would neither dive or would the known buddy system be compromised. What would be easier, packing a pony or re-selecting a known, dependable partner from the available vacation buddy pool.