DRC isn't too new, that has been around since I worked there (2001). It is true, that currently bookings are very high (I think around 90% on average, from what someone who would know told me). I have actually seen figures in the mid 80% range also, but suffice to say - the last couple of years have been very good for Disney.
However, if September was THAT good normally, Disney wouldn't have offered
free dining. Now they have a new offer, in addition to AP/Fl Resident discounts. I consider September a slow time period, possibly the slowest now (January seems busier than it once was). Overall, it's been steady through most of the year. The highs don't seem as high, the lows not as low - though September is still a very good time to come if you don't want too many lines.