Hi RKing, thanks for that. Over the years I've used and/or tried quite a few different powders. I do use a number of different powders for several cartridges, gauges, and purposes. I agree with what you're saying--narrowing down to only one powder it current conditions would be unnecessarily counter-productive to perfect load development across all scenarios. My main curiosity in posting the question was simply what the choice would be for the single, one do-all powder choice of this really knowledgeable sample of reloaders that frequent the cast-boolit forum. And yes, I do love the 8x57. I've done some casting and shooting for it but my primary shooting with 8mm's has been reloading jacket bullets for it for hunting. I won't publish the load I finally worked up for my scoped Yugo pushing Nosler 180g Ballistic Tips, but it's a (nearly) tack-driving cannon. I'm currently working on getting a "good enough" load for it using the LEE 175g and Karabiner bullets. Some little success with those but not good enough so far.
I'm just dumbfounded that I never tried Unique or Red Dot over the last couple of decades. If for no other reason than broadening my horizons and experience, I am going to get some Unique and Red Dot and try them in several applications in 2019. In the future, if powder choices become scarce again, but a guy wants to stay in the game with all of his/her various shooting hobbies, these two powders really seem to be a good choice to have a few containers on hand.
I'll say it again: a big thank you to all of you for educating me on my favorite hobby.
8mmFan