I can address some of your points, but I am limited by time until maybe a couple days from now when things ease up. Cable box works fine with Cox remote, I have had the current box for a few years now - it's just the TV in that room I upgraded. Not sure I know what you mean by "what code blinked back at you". The vizio is a SV370XVT which ships with remote VUR9M Remote Controller, Part No. 098003059100. The instuctions to program the vizio remote state to just turn the cable box on manually, then press the cable button on the vizio remote, then hold the set button down until it blinks twice (it always blinks once right away, and then a double blink a few seconds later). Instructions then say to enter the 5 digit code and if it blinks twice that should mean it works. What I always get is just a single blink after entering the code. The process does not use the remote from the cable box, as you would if one was programming a learning remote (which another one I use is).

The cable box is Scientic Atlanta Explorer 4240 HDC with the remote looking like the ones pictured in your first link. The Cox website now shows they use a newer 8000 series that I can switch out for if there was a reason.

I sent a email to Vizio support and they will reply by end of the day 12/31.

(Also just got a new Dell laptop, desktop, and new wireless so it's been a hectic few days trying to get everything up and running).

Again, thanks for your help. I'm really quite amazed by this forum.