Well, don't know about the black and the silver one, but I find myself using the 670 a lot, and on a lot of different things - drums, guitar, mix buss. I'm definitely checking the black one next time. 

I also thought that I'd give their Pultec a try last night, after being so impressed with the 670. Messed with it all day - first on an acoustic guitar. I was almost sold right there and then. Found it so nice and easy to adjust that I bought it tonight.

I dig those singles. :)