I think Lone Peak makes nice bags. They are very light but plenty sturdy.
I used the P99's as front panniers for fully loaded touring, and as rear panniers for credit card touring. I did a 4 day CC tour with them and they weren't full. They have worked fine on 4 different racks for me --Tubus Cargo (rear), Tubus Tara (front), Blackburn Custom Lowrider (front), Jandd Expedition II (rear).
I really like the way they open up all the way, it's really easy to pack them. A trash bag inside takes care of waterproofing just fine.
You do need to make sure you get hooks that match the diameter of your rack rails. If you are ordering from Wayne at www.thetouringstore.com
he has both sizes of hooks. Aftermarket spare hooks can be purchased if you change rack size later.
Rear panniers are generally larger and some are asymmetrical to help reduce the chance of your heels hitting them. The only thing that might go wrong with your plan is that those bags are probably too small for anything but credit card touring or ultralight camping (no cooking gear, tent & sleeping back on top of the rack). I don't think you will regret having them as front bags later when you get bigger rear bags.