I imagine a lot of Fairchild buyers will be looking for Beatles-style compression and this delivers. It's fantastic on vocals and drums. But one thing I learned from a random YT video, which the UA manual only hints at, is the 670 version is noticeably different from the 660. (I'd always thought it was just a stereo version of the 660.) You can't get that Ringo-style snap on the snare with the 670, only the 660. The 670 is much gentler and perhaps would work well on busses and full mixes. Yet to try this, however.