The 170 and 175 have pretty similar burns. We fly both regularly and switch between them on a leg basis. They handle identically. The only difference in limitations are the weights. According to the CAs who have flown both the 145 and the 170 series, you don't have nearly the flexiblility in fuel burn control in the 170s. Over a 2 hour flight, its usually about a 500# difference to go at .74 vs .80.

If fares are able to rise in the aftermath of consolidation, I think you will find the E-Jets outperforming the CR7/9. You will end up with a more discriminating passenger who will hunt for comfort with their higher fares. I also don't see mainline carriers operating the CRJ on their own certificate due to the "RJ" stigma attached to them.