Considering the information came from a Master rigger (3+ decades), ex Para-Phernalia manufacturing employee, Dealer for Softie, and over 10,000 jumps, I am pretty certain his information is accurate.
Making assertions about operator error if using a round chute and not with a ram chute and using that as reason for possible performance differences is ridiculous.



Not true. They are equal or the square is a bit faster. Either way opening time variances between the two overlap. Besides a handle fumble or pilot chute kicking around for a second before inflating will burn far more altitude than any difference between round/square. If I was in the business of selling pilot rigs I would go to the big contests pay a young durable skydiver to jump a round, then jump a square afterwards land and open my order book. Guaranteed every pilot who saw the difference live would bust out a credit card.