
I've not done it although I very nearly did this year (ill health stopped it), I have helped out in a proper husky rally at the start of the year though with my friend who does full rig running and scootering. Very fun, very hard work though as you do have to help the dog sometimes!
Also essential to have a dog that won't suddenly dash off to see another dog, or chase a squirrel etc (or at least has a solid 'leave' cue for while they're in harness).
I would still love to do it - my youngest too would make a fantastic running pair, I have been working on their directional cues again lately and last time we lead walked they were in front of me, perfectly level with each other and went round a corner we don't normally go round on cue, in perfect sync with each other. It was ace lol!