Going back to your questions about the sonic benefits of getting a tubed preamp and a SS amp, it has to do with the sonic qualities you might like. Bryston, is fairly neutral but to some, this might be too cold or unemotional. When you add the right tubed preamp, it will add a sense of warmth that will allow you to listen longer without getting sonically jaded.
Of the two choices you mention, the Sonic Frontiers Line 2 is known to be a more restrained or neutral tubed preamp.
The BAT might have a more traditional or robust, emotional presentation.
The Bat, even if it does not have the phono board, might allow you to get fitted with one from the factory, because the new, X designation model of the VK-3 might use the same physical dimensions. But, the phono board for what I can remember it was around $500 alone. You might be better off purchasing a different phono stage later.