OK.
I got BAT VK-200. It replaced Linn AV5105. With a few days of careful listening, I could easily tell that, compared to Linn AV5105, VK-200 is a better amp. Intially I was a bit disappointed, maybe because I was expecting night and day change, but after I became more realistic and with more listening, I would eadily feel that BAT is more powerful (bigger and louder sound with the same volume level). Most notable is deeper base. In some music, it got a bit boomy, but in most music, pretty tight and fast.
Also, better in almost all sound reproduction categories I can think of -- wider sound stag, more dynamics, more clarity, ...
Overall, it was a nice move. Linn is still pretty good in its price point (used at $500~600) but vk-200 is a clear winner. It may work better with vk-3i or other balanced preamps, but Rogue 99 Magnum mates pretty good. I may not be able to tell how good until I try vk-3i or other balanced preamps, something I would puruse in the future.