Hi Dan,
It is hardly a fair comparison for the Rega brand, as mine was an entry level, lightly modded RP1. After having done the A/B with the Classic and Amadeus, then having swapped the Amadeus into my existing system using the same cart as was on the Rega (modest but perfectly serviceable Nagaoka MP-200 until I save pennies for an upgrade there), the main difference is that there is more of everything good, musically, and less of everything bad (motor noise, runaway bass resonance, electrical noise). What a treat to power up the Amadeus and hear nothing but inky silence before the needle touched down!
In terms of liveliness and open, engaging sound, I think even the Rega bested the VPI, though it had nothing approaching the level of refinement and poise of the Classic. Both the WTA and VPI pull more detail from the grooves, but I get the feeling that the VPI merely brought those details to my ears, while the WTA pulls me out of my head and into the music. Zoo versus safari. IMO, the WTA gives me all the involvement, engagement and joy of the Rega and close-to if not all the sheer detail/accuracy of the VPI in one package.
One difference that I was not prepared for (though should have been, having read enough and understood the different designs) in the switch from my Rega: the WTA is very much more sensitive to movement/vibration than the Rega. In my old, springy-floored house, the Rega was largely immune to all but the heaviest footfalls (tracking-wise), while with the WTA playing my dog can walk through the room and cause it to jump the groove! I plan to install a wall shelf as soon as I can which will hopefully alleviate this issue but this sensitivity surprised me. The Rega did amplify footfalls and room-borne vibration and resonance (which the WTA does not), but did not get pitchy or jump the grove as the WTA does. Not sure about the VPI as I never subjected it to my trampoline living room, but the WTA will not forgive my sloppy placement/floor deflection as my Rega did.
Hope that helps a little - Matt