Why don't you go for the BMW ones? I think their excellent; they're waterproof (I've ridden them through some torrential downpours), they look good and the simple but very effective expanding system is superb.
I have used Beemer panniers for 16 months. Excellent. Totally water-proof and the expansion system is very good.
However, I suggest that you ensure that you insist on getting them supplied with keys matched to ignition key - no extra cost - why carry 3 keys when one will suffice. (unfortunately some dealers don't like the hassle! - Crewe certainly didn't!).
Well having seen the construction of the Metal Mules at the Booly show, I would go for those. Pictures don't do them justice. If I could flog my GS panniers I would buy a set straight away. The grey powder coated ones would match my bike perfectly.