Very interesting reading in this thread. Not many people would advocate not complying with state law on a public forum, so by default we are left with comments aimed to encourage compliance.
There are doubtless many registerable items in the hand of non-FOID holders that are in the real denominator of compliance percentages. When this act was passed I considered it to be penalty enhancements for people committing crimes with banned items, sort of like how FOID is used. When someone commits a crime they charge them with everything possible and use that to make a deal. So now instead of a felon with no FOID robbing someone with a Glock that has a switch, they will be able to add the extendo clip and the threaded barrel under PICA to the pile of charges. Instead of giving them 10 weeks, maybe they will get 12 weeks!