As to the actual clean no not really Ive never noticed much difference it definately makes a difference to how long it stays clean for.
The super HD £11 thing has some nice hydrophobic action going on taking that nasty dirt infused rain away from the vehicle. A life saver if a black car 🙂
Motability wise due to lease length you wouldnt really notice the benefits but if it was a private car and your keeping it for 10 year you would see the beneift from the occassional top of the rung clean especially if a slaty muddy area as it usually includes undercarriage clean and protection