I just have to say DAYUM.
I cannot imagine having 100 pledge sisters and having 400 people in the chapter. Logistics must be a nightmare. Where do you hold chapter meetings - in a lecture hall? Where and how would you do initiation, and wouldn't it take forever? (I know one chapter at my school took 25-30 new members each year in FR, and divided each NM class in half and held two initiations - and that was for only 25-30 NMs.)
These are situations where expansion is certainly called for, but unfortunately, the barriers to entry (must have a big house from the get-go, must bring in 250-300 women in the colonization process (and imagine THAT initiation!)) are just too high.