I really don't know which airline has the longest flight using an EMB... In Brazil, only RIO SUL (Varig's subsidiary) uses the EMB-145 and only for short routes... But, which one is the longest route??
Jetmagic, the Cork, Ireland based airline with two ERJ 145s and one ERJ 135 has quite a long flight from Cork to Rome Ciampino. The flight takes three hours. There may well be longer flights out there, of course, but three hours is pretty long in my book!
Yesterday I flew in a Luxair Emb-145 Athens-Luxembourg with a refuelstop in Milan-Bergamo. Pretty long distance (also because of a ATC strike in Italy) for such a quite small plane. Anyway Luxair's service was excellent and comfortable.
CO's crazy for putting people on a 4hr RJ flight to OKC. TUL is going to be next with 3hr45min flight time. I would never fly an RJ for that long a period of time. When I heard they were using it for FPO I thouhgt they were nuts. i honestly didn't realie OKC was 4hrs away. And I'm all nervouse about my 2hr30min flight from TUS-IAH on an RJ.