Thanks guys for all your replies, and obviously I didn't mean the question to get too controversial, maybe I could of asked the question differently.
I think the general consensus is that for Air Guns muzzle down is the way forward. The you tube videos of IPSC are something else - rapid fire tactical shotguns
Obviously very different from air guns and therefore they do what they do. So I will tootle off without further adieu.
Cheers & keep your ****** up, but your muzzle down.