I am with elevens on this.It's another brilliantly stupid idea, same league as the mini-dumbells. I'd like to see the test data that defends those two "features"
I have yet to see Givi or any of the other luggage manufacturer adopt this sliding concept.
It is designed to help with the handling as you tip into a corner.
Not something that I would particularly like as it upset the weight distribution as you are tipping in. Probably up there with Honda VTEC that kicks in when you least want it.
Personally I would bypass the slider set up and bolt the mounting plate up solid to rack to stop it moving and rattling.