Hmm.
I've tried both. Before you get me wrong, kindly understand that I'm a player who relies on individual pedals for tone, this affects my perspective on either amp.
The things that set the Valvetronix apart from the Pathfinder are the obvious inclusions of amp and efx simulations. However, it took a long time for me to tweak before I could find a usable tone on the AD15vt. What's more i personally find the whole idea of saving efx and amps together in one channel rather troublesome for that amp. However that said the amp simulations and quality of sound from the effects are very impressive.
Right now I'm using the Pathfinder 15R and it works very well for me because it's a very simple amp, with minimal hassle and very few things can go wrong. It takes my pedals very well, and has great low-end response even though i still use my EQ pedal to add more 'presence'. The built-in Tremolo is seldom used, and the 2-band EQ knobs are very interactive with one another. The Reverb may not be as echo-ey as fender or even marshall units, but it helps to add that little bit of dimension to your sound.
Last but not least... VOX IS FOR THE BLUES!!!