The emphasis in a slip jig is also very diferent to the other jigs when used for the 'Feis'. There is a hard beat every other bar (sing Rocky Road to Dublin) which puctuates the dance and changes it's direction.
For irish dance music played at dance speeds and emphasis listen to John Doonan 'Flute for th Feis' - he is one of the best dance musicians around and the spare arrangements allow the beat to come through clearly.
If you are ever invited to play for a Feis don't!! I did it once and had to play the same 5 tunes, in strict tempo, for 6 hours!
All the best