I never use the internal metronome at all, and I use time (H:M:S:F:SF) for the location base, not meter. I do that for two reasons- one, so that I don't have to screw around with tempo mapping stuff on the 1624, and two, because it's familiar to me from older technologies that thankfully existed before tempo maps. I literally treat the machine as a 16-track tape machine with an autolocator- nothing more.
How I edit depends on what I'm editing. I edit by ear when I edit on the 1624, anyway. I don't do elaborate, "sample accurate" editing at all for most of my material: I just edit to arrange, just the way I did with a razorblade and blue tape back in the day. Scrub, mark, scrub, cut, don't look back. You can tell that much of the music I do bears *no* resemblance to modern sequenced/loop-based music... (;-)
Having said that: when I need to do the kind of stuff that must be rigidly metered (to sync with a synth, or to track my E-drums to MIDI for later hackery and experimentation with these here newfangled pooter musical forms), I set up Cubase and track *simultaneously* to Cubase and to the 1624, with the 1624 as MTC master and Cubase as slave. If I need a click, I derive it from Cubase, and set up any needed tempo maps over there. The 1624 simply provides a safety- so that if Cubase shits the bed recording audio (as it sometimes does, though less here lately), I still have all the tracks on the 1624 and can fly them back in later. Cubase usually doesn't lose the MIDI data, so the 1624 provides an excellent safety net, since I have never yet seen it fail.
It's interesting: I'm really developing two completely different working styles. For free-form, improvisational music (jazz, jams, straight rock, songwriting explorations, and my wife's a capella vocal stuff) I track only to the 1624, and just use the Hammerfall's Digicheck program on the computer to monitor the ADAT streams and give me high-rez metering that I can see from anywhere in the room (*exceptionally* useful when I'm playing drums...). For structured, possibly sequenced Elektrik Muzik, I go ahead and track to Cubase for its MIDI capabilities and click generation, and use the 1624 just as a safety. At that point, I can do all my strongly metered editing in Cubase, so that everyone can hear my mistakes repeatedly instead of just once. (;-) I do very little of that type of work at this time, as you can tell. Gonna take me a while to warm up to it.
I always said that I'd never track to a software package. I lied. However, I *will* now say that I'll never track to a software package without a safety! It has saved two or three really good takes with a couple of collaborators... But I'm just a belt-and-suspenders kind of guy...