I'm still using them, they mostly play the same. Quarters now has a box check vs. compressed sets and match principles were put back on to deep half zones from the Cover 6 and Cover 9 plays.
Outside quarter zones aren't playing as well for me 1-on-1 on the outside so I'm mixing in more man coverage against tougher opponents. Cover 1 Robber or 2 Man Under can be dominant if you are smart about what you do with your safeties and zone drops.
With defenders being so slow to change direction double crossing routes, meshes, etc. can be trouble and there isn't much you can do but hope to play better on the next down.
Let's say you like 2 Man Under but you keep getting killed by a deep crosser. Set your curl flat depth to 30 yards and hot route the safety on the appropriate side of the field - no more worrying about the crosser.
If you have a guy with Flat Zone KO at safety they can do damage because they will get awesome breaks on throws to the flat even from depth.