As a fellow Vintage owner, I've finally managed to catch up on this thread. My thoughts:
Rob, let the speakers bed in and also play more with your amp EQ. I can get a very 80's grindy rock tone (think Queensryche, i.e. hartke 10 inch speakers and a GK amp). So the 15s are not the problem, it's (probably) the way you EQ. That said, from my experience on the Big One vs the Vintage, I think you may prefer the Big One as it would probably be "easier" to dial in the tone you're after. Maybe.
The construction of my Vintage is top notch, it's been thrown in and out of the band van countless times by our less than gentle crew and it's survived fine.
I think the cab is worth every penny I paid and I'm incredibly happy with the sound, the portability (one hand lift and I have the "old" ply!), the construction and the service I've had.
There. Lovely!
Mert