Sorry, DA is a dual action polisher, like the Megs G220
Are you after a protection product?
P1 is a polish which is used to remove swirls and light scratches. Colli 845 is a wax, which you'd use to protect your paintwork, so totally different things. The GTechniq equivelant is C2 sealant. However, if you're after a decent wax to protect your car, then Colli 845 is a great choice - it's one of the most durable and easiest to use out there. Plus Waxamomo does it at a great price! (£13 I think?)
Just remember to give it a good shake up when you get it, as it gets quite gloopy when its been sat for a while.
Hope this helps.
Russ.