Jeff,
"In other words, if an SMAW, GTAW, SAW, FCAW, GMAW or whatever says 70ksi min then go with that. For the great majority of applications strength differentials may be interesting but are academic."
Wise words...
And as I guess, the weld metal deposit's strength may rather not be the subject of matter.
To my best knowledge the consumable(s) or filler-material(s) respectively, is/are produced to provide rather "higher" or "better" mechanical properties compared with the base-material(s).
Exceptions (e.g. ultra-high-strength steels) may prove the rule.
What is rather quite more interesting is what you have described so excellently in your post:
"To design by the strength differential of processes (...) is a very sophisticated and detailed process and requires heat lot control of materials, control wof WPS parameters, and chemical limitations to work."
Great!
If you don't mind that I say so, but this should point us exactly in the right direction.
Best regards,
Stephan