I'm the OP, chiming back in now that I've been listing vertical for a few months. So I did try horizontal bi-amping for a few days. Then I tried the vertical config. No contest. Whatsoever. The vertical made everything bigger, louder, clearer. Sold my beastly Magtech amp shortly after, that's how much clean power these 2 tubes amp crank out.
I sent my pair of 10' Fidelium cables back to WY so he could cleave in half with proper ends, ergo now have 4 separate single runs to each blade. Matchy matchy.
To clarify: I have two stereo amps, total. One for left channel, one for right. That's what vertical is. Horizontal is something else.
Anyhoots, anyone else discovered the wonders of vertical?