I have had two VTL amps( 60/60 deluxe and triode30), got great results with VTL preamps in the chain, and it is an easy sell if you decide to change both units somewhere in the future.
I would stick with VTL myself, not that I have heard any of the VTL items you mentioned I just believe in system synergy.
I heard a Bat pre (it may have been the 3i I do not remember) I think it was the 3i and the Rogue 99 Magnum was clearly better in my system. The BAT made me want to sleep as it was too smooth. The BAT had new tubes so they can not be blamed, also I may have had the Rogue Magnum 120 amps at the time.
FWIW my 2 cents...