Scott,
Hi, glad you joined in the discussion. Yeah we don't have the traffic levels you have in the States, so I could understand you might use it to express some urgency to the PICs. I just don't think it's a very good technique.
From my experience there are a number of aircraft types that always climb at best rate. For instance, the Brasilia, flown in Oz for some time, always climbs at it's best rate. Ask it to expedite, and nothing changes. The DASH 8 is often quite similar depending on the model and the company that operates it. So you can't rely on "expedite" to speed an aircrafts rate of climb.
Catchyalater
DP