Comment 1 for bug 1114643

Luckily, almost 99% of modern dance music is composed in a 4/4 signature.

You can't mix a non constant BPM track the classic way because the beats distances vary. So what can you do?
1. Play the track completly.
2. Most tracks have some breaks, i.e, silent parts with no dominant bass. Bring the next track in is a good idea.
3. Use effects
4. Make use of scratching
5. Bring the next track in using a fast-cut. Very sophisticated because you must know your music, i.e., the next track must fit the current context or key code.