Oh yes they do. At my regional I was on the CRJ-200 the whole time and I was chosen for the Emirates one-day assessment at Atlanta. Those successful would then attend a shortened 2-day interview in Dubai. I emailed back saying I was interested and would see them in Atlanta. They came back with a form that asked me to break my flight time down with a list of flight time of time in more than 30 ton aircraft and less than 30 ton aircraft. I sent back my CRJ-200 time and they said I wasn't qualified because they currently require time in a jet more than 30 tons. At that same time, I know guys at my regional that got hired at Emirates and they were on the CRJ-900. So yes, Emirates does know about the 50 seater CRJ-200s and ERJ145s, and they do know that the CRJ-7/9 and E170+ weigh more than 30 tons.