G4/AGP sawtooth/digital audio advice?

[Hal]

I'm in the process of considering buying a second G4 system. I 
currently have a G4 Cube (which I love) but I need a second desktop Mac 
and would like one I can open up and work on more.

I'm not looking at new systems (I tend to be a "trailing edge" guy and 
enjoy tweaking systems), rather I'm considering buying an older 
Sawtooth or "Digital Audio" box that I'll eventually upgrade as needed. 
I've seen these going for fair prices online (under $600), but am 
wondering if the premium for the Digital Audio version is worth it. 
They tend to go for a little more money, buy obviously you get a 4xAGP 
slot, another PCI slot and a 133mHz bus.

Any insight or input into this decision process is appreciated.

thanks,
-Hal