I spent about 2 hours with Traktor trying to start a mix. I think I got in about 5 tracks at my farthest. Though I think I learned a bit, I think I have a long ways to go. There's just something really tempting about loading up several hundred of your favorite tracks and going for it.
But ... though it does a pretty good job of helping you beat match, it's off just enough, enough of the time, to hang you if you lean on it. I think some more hours in the cockpit with it will get me sorted, though.
Another thing -- old records had human drummers, and the tempo is all over the place; something Traktor tries to follow, but you pretty much have to push and drag all the way if you want to mix them. Anita Ward's "Ring My Bell" is a case in point, which actually SKIPS a fraction of a beat going into the chorus, and the chorus is nearly a whole BPM faster. After the chorus it drags back about a BPM. Could make you look a real fool.
I wish there was a tool that let you take a track, mark all the downbeats, and then have it time stretch them all to a common tempo.
Oh, and I'm convinced some things I've downloaded were recorded from vinyl on a turntable with very slight variations in the rotational speed; not enough to notice normally, but enough to trip you up mixing.
It's amazing sometimes to consider that beat matching means cuing records with accuracy down around 10 milleseconds. The ear measures tempo variations down around the same range. And this is with a fairly large lag between your ears hearing something and your mind being aware of it. It's amazing that people can DJ at all.
But then, when I think about all the complete fools I know that can DJ, maybe it's not such a big deal after all.