I too run mine into an Ampeg rig, PF 350 and 2xSVT210AV´s. I have both pedals and they are similar, but still different. Haven´t got much Fender experience, but I guess, as others have said, VT has a baked in Ampeg quality and the AS has a baked in Fender quality. Neither has given me exactly what I want, which is a mild organic tube drive. Both close, but the VT quickly gets to honky and nasal (perhaps its the 2xAmpeg-thing??) and the AS has to much going on in the mids and I keep having to adjust and cant quite get it right. My rock/cover band recently hooked up with a second (tube-rigged) guitarist, so I´we dialed down my need for overdrive and been going more for a solid bass foundation to our sound. I´we lately more or less used only my Barbershop into comp for an always on mild drive. That never fails! I´we been using my VT as a heavier drive, with Character a good bit past noon, which seems to work well, honk free. MY AS is at the moment set clean and as flat as I can get it, as a boost into the Barbershop, which also works out nicely

P-bass->Barbershop->comp->SS Ampeg. Don´t really think i need anything else. To improve I think tubes would be the only way