It's also difficult to use EQ for taming peaks because they vary from seat to seat. A frequency that rings between two walls will ring for every seat between those walls. So it's more productive to use EQ for decreasing decay time, because it will be beneficial over a larger area.

Personally, I would use EQ to address some of the ringing and use physical treatments for smoothening out frequency response. Their benefits will overlap at some point.

Still, I would be curious to hear Jack's results with SNAP. If it can provide any benefit, then that's better than none at all.