Yeah, I have had a mixed bag of success with that. I'm currently going round and round with a 22 ARC and I want a pretty long rail on it. I've got a full length Arca on the bottom and 1.5lbs in side weights. With a ckye pod the rifle weighs 18 lb. POI will vary greatly depending on shoulder pressure, cheek pressure or head weight, and grip. More so on this gun than any of my other AR-15s. I would agree with you for a standard 13 -in handguard on a 14.5' or 16" barrel. I have two 14.5" & 16" 223Wylde and they shoot Sub-MOA without any handguard theatrics.
Right now I'm looking for uppers that offer that