The potential hitch is that the EMB training slots may be full when you show up for class (having chosen ORD or DFW) and thus CRJ and/or Saab may be the only equipment available at that particular point in time. If you want to absolutely, positively guarantee yourself the EMB then you need to hire into BOS or LGA. After you are in the system and assigned EMB training then you can put in for a transfer to any other EMB domicile. Is it very likely that you can choose ORD and expect the EMB? Yes, but it's not a certainty. FWIW.