I do not recommend the Schaller system. It's seriously flawed, IMO/IME.
Care to share details on this seriously flawed
The only reason I dislike the Schallers is that if the nut comes loose (which in my experience, it often does) the whole thing just falls apart, and off comes your strap.
On the Dunlops, the little clip holds it all in place, and makes it pretty much impossible for it to come undone.
I've used both in the past and never had a problem with either. I just think the Dunlops are a better more fail proof design.