I got this pair as dime size juvies so I had no idea what sex they were initially. Mine just turned out to be a M/F by dumb luck. The only obvious differences that I can visually see is that the male has a thinner breeding tube. They do the exact same ritual of shaking at each other that you spoke of prior to egg laying.
look at the tubes coming out of them just in front of the anal fins. there is a little tube. the females have a wider, blunter one than the males thinner pointer one.
Cool tank ya got. By all means, steal the post! it's kinda old now. My angels have laid 1,000 more eggs since I started this thread LOL. Anyone else out there with angel spawning pics? Post away!