comparison quest or bmw system3

a friend who i bought my gs off in january has decided to sell the bmw gps system he got with the bike when he bought it new in 06. it has all the bmw fitting kit included .
would the bmw system be any better than my quest (which i am happy with but am wondering about storage space for when i go to europe next month) should i sell my quest and buy his bmw system or just leave well enough alone.

The BMW GPS has all of Europe pre-loaded, is touch-screen and a doodle to use. If I had to pay more than £400 or so for it, I would rather have the Zumo 550.

thanks that answers my question perfectly