A few quick notes here, it didn't
take Bombardier all that
much development money, to come out with the -900. It's really a very
straightforward derivative of the -700 which actually is a much more notable variant itself from the original CRJ airframe, than the -900 is relative to the -700. (Read some of the press clippings, even Bombardier RJ quarterly pdfs if you like, and see some of the remarks that tend to bear this out). The BRJ-"X" --with a whole new airframe design, a whole projectnew project from scratch just like the E170 or F/D 728-- and would have been a huge capital-intensive and strategic, corporate, engineering and marketing decision all across the board. So, really tough to compare the two. It's even a bit tough to compare the bigger CRJs with the 170, and even more so the 728 which is going to feel more like a 717/DC-9 in the cabin, than anything like a traditional sort-of-cramped regional and/or commuter aircraft.
worthwhile to ask what Bombardier intends to do with its airliner business, say, 5 or so years down the line when likely just about all its RJs will have already been shipped. But that's another story, a planning issue and not related to the current market climate and sales concerns for bigger CRJs.
So in the meantime, the bigger CRJs just sell on their strengths--namely being first to market, and as well, offering "fleet" prospects for existing CRJ operators, especially the bigger --yet still regional-- ones like Mesa and Horizon who don't have scope clauses to juggle around so decisions to get even -90 seaters aren't impacted by any of that like they still are so much with the mainline carriers. I don't even think Bombardier is counting on anywhere near the sales numbers for the -900 than for the -7s, not even over the product's lifetime of the next several years.
Me I'm more concerned about the fate of the E170 whose only advantage that I can see over the F/D 728 might be price, just as with their ERJs. I think the 728 really might to be an aircraft of choice --and so a series based on it more of a likelihood-- when it comes out, and Embraer might be left a bit high and dry after its initial round of orders are all filled. Still very soon in the game to speculate about all this though
Especially with neither aircraft even taking to the air yet.