I've not had any problems in recent times either and going but the comments on the boards, not many people have. There are always whingers I see, but they are in a minority. I don't think I've waited more than 10 minutes or so in the past few months.
Still, the main problem with the "stand on the number" approach is that you could be stuck behind a slow person and also anyone who is in the position closest to the xray machine can often be waiting ages for a gap in the trays. Also, you can't really prepare while you're waiting behind someone, so it's really just moving the queue to another area. I'm not sure that it's the best system, but EDI is not alone in using it. A lot of airports have adopted the method. At least EDI seems to have sorted the staffing issues and things move a bit more smoothly now.