If by scan and go you mean registering for a handset and then scanning each item as you go round the store, then yes, I absolutely love it......... I use Waitrose's Quickscan.
I hate all the fuss of loading the trolley with goods, unloading them at the conveyor belt, then packing them all up again. With Quickscan, you only handle the item once instead of three times, you can pack as you go round, you can see the running total of what you spend, and the handset alerts you if there is a special offer, such as a reduced price for multibuy; I'd have missed a few offers if I'd not had the handset.
If in a supermarket that doesn't do this system, though, I always use the manned check-outs as I hate the self-scanning machines. I always have something that needs checking....alcohol or paracetamol or something, there's not much space, and the voice of the machine drives me absolutely bonkers.....I usually end up having a row with it! :-D
Plus, if my shopping bag already has something in it bought elsewhere, the machine goes bonkers.
Then what with vouchers etc., it all takes ages.
No , you can keep those machines.
So, Quickscan handsets ......yes!
Manned check-outs......yes!