For what it's worth, if people are still concerned with verifying the sources of these rumors that some schools are increasing their class sizes, I can say that the dean of admissions of one
highly ranked program in the midwest made it a point to tell me that another
top east coast program where he/she used to be the dean of admissions was going to add another section this year. I was actually very taken aback by this, and in my eyes the comment actually did more damage to my view of that admissions officer's current program than my view of their old program that was apparently adding a section.
In NCAA sports recruiting, there is an unwritten rule that no coach should ever engage in "negative" recruiting. That is, get recruits to join your program by selling your program, not by trashing another program that you know they are considering. I was very shocked to see the face of a program (to prospective students) engage in negative recruiting by trashing his/her former employer, especially when the students from that program were making an effort to not speak poorly of other programs, but my point is that the heads of admissions from top programs are pointing out that other top programs are adding whole sections this year, so I believe these claims shold be taken seriously.