1. If you'd really like to try a recipe, call Ballistic Products, buy a small bag of their 1 oz, PT1260 wads and they'll give you trap appropriate recipes. By 'trap appropriate' I mean with a speed close to what you're shooting now. You might was well buy some #7 shot from them while you're at it.
2. With all the hollering about the evils of steel here lately, you're willing to stick your neck out and ask such a question? My advice to you is to switch to #1 above and get yourself some direct experience with the stuff. Then when you hear the hollering you can see that it's just a matter of personal choice - at this point. And I hope it stays that way.