I can vouch for the swaying with a cheap rack. I have a Trek rack on my 7.2 FX and I have a Surly rack on my Cross Check. When loaded down (two twelve packs of Mt. Dew, for example) the Trek sways but the Surly is rock solid. In fact, I don't even notice the load on the Cross Check.

I commute with Arkel GT-18 panniers. They're my work horses. Fine panniers. A bit expensive though.

I also have a pair of waterproof Axioms. Before the Arkel's, I used them for 5-years and they never let me down.