I am a P w. rounds player and I briefly had the 64 (and the SV as well). I only played them using the cab sim on the XLR out.
The Fender tone stack really confuses me A LOT and I struggling especially with "missing" low mids with pick playing.
I wish I had giving it more time to explore the amp out into a DI, though.
On the other hand I really enjoy my Empress ParaEQ Deluxe/Cali 76 combo.
The Bassrigs really only make sense when you can use them for EQ, DI and magic sauce at the same time.
I'm curious about their interpretation of the ampeg 8x10 cab, though.
The last time I played a vintage 2x15 cab I did not like it at all, but the last time I played a Fridge, I loved it.
So the XLR out on the Super Vintage could maybe be more useful. I would like to explore that route because I actually have need of a beefy tone that works well with distorted guitars.