Yes I have opened up plenty of shells. I have not found a square pellet ever. The experts are not perfectly round. every pellet from an expert I've seen has a flat spot on it. I have not seen much of a difference in size.
The whole point is they are what they are. They are an inexpensive shell that uses cheaper shot than the more expensive shell. They are not guaranteed waterproof. They are $6.50 - $7.00 per box for 3" and $9.00 per box for 3 1/2". Kents are usually about $3 more and drylocks, nitros, or federals are more than that.
If you are only going to buy a couple boxes a year get the expensive stuff. If you are going to buy a couple of cases or more, the experts are a very good value. Just do not blame the shells when you do not kill a slam dunk shot. If you shoot at a duck within 30 yards with anything from 6's to t's even with a cylinder bore choke ---you center the duck ....the duck dies ....period. Is it possible for a duck to fly through a pattern - yes . Is it likely to happen under 30 yards? NO! Like I said the more you practice ....the better your shells get.