DiPinto instruments are outstanding, and living in Philly near DiPinto's company shop and headquarters means I've played several. I've had a Belvedere Standard for almost four years. It's an amazing bass, with huge yet clear tone, and excellent construction and playbility. I've heard nothing else that sounds like it. My only gripe is the long reach to first position created by the short upper horn that doesn't reach the 12th fret. (Other basses, like G&L's ASAT, have this issue.) If you run a search, you'll probably find some of my posts, and I've reviewed it on Harmony-Central.com as well.
I'm not as fond of the Mach IV bass, which I think has the same pickups as the Belvedere, but in a solid body. I've only tried it a couple of times though, so I don't have strong convictions about it. Bass Player gave it a positive review a couple of years ago, and I'd like to spend more time with one. The Galaxie bass is a very cool take on the P-bass, but I think they make only the Los Straightjackets model now.
The Mach IV guitar, on the other hand, is great. One of my band's guitarists bought one a few weeks ago, and I considered one too. The bridge humbucker is actually two side-by-side single coils, and has more twang than a typical 'bucker. The more I hear, the more I like.
"Ignorance is common, but in a learning environment it cannot be tolerated as a permanent condition." Beverly Daniel Tatum, President of Spelman College.