For whatever it's worth if your "realistic" use case involves a two occupant load most of the time the A/R/X 8 is massive...and a bit of a waste. And the A7 will be quite a bit bigger than the 6?? More energy, more chemicals, more water, bigger cover, etc and so on. Go with the 6!
I have an A8L. Looking back I do wish I had saved myself a few jr bacon cheese burgers and gone with a smaller tub. I also, looking back, would not repeat the lounger. My dealer even told me "most people get a lounger on their first tub, but not their second". In my case he will be spot-on though I hope to not buy a new tub any time soon.
I personally wouldn't worry about one pump vs two. For us they're either both on, both off. Having the flexibility to run one or the other is only useful when I toss a capful of dichlor in and want to leave half the tub running after I close the cover.
I believe I could be quite happy with an A6. Whichever way you go I don't think you can go wrong with a Bullfrog. I think there are 5 in my neighborhood now. Great tubs...