"Unidentified airlines"
Hmmmmmm, let's do some deductive reasoning. It's not Skywest, Republic, Horizon, Comair, Pinnacolaba, Compass, AirWhiskey, Island Air, Mesa, PSA, TSA, XJet / ASA, Piedmont or Eagle due to longer upgrade times and relatively high mins for hiring.
That leaves Cape, CommutAir, GLA, and Silver airways. Though I'm willing to bet a good portion of CommutAir pilots have 1500+...which leaves only the B1900 operators....oh yea, and G7
Sounds like the testimony was a well-rounded, unbiased representation of regional FO's to me