"Kyle Boatright" wrote in message

I understand that on some turbine A/C a standard procedure is to calculate
the power setting required for a given runway length, weight, density
altitude, etc. On takeoff, that power setting is used instead of full
power, saving wear and tear on the engines, and reducing noise and fuel
burn.

That's correct. A "Reduced Performance Take-off" would have to be
specifically allowed by Comair's OpSpecs, and then there would likely be a
long list of conditions prohibiting its use. We used to have ten specific
conditions that could kill an RPT. Eleven, actually, as Captain's
discretion was at the top of the list :-).

I can imagine a scenario where the pilots used a power setting calculated
for a 7,000' runway, whereas full power *might* have allowed the aircraft
to safely depart from a 3,500' runway.

I have no knowledge of the CRJ, but I don't think so. The power reduction
in a near-gross-weight airplane was enough to save a noticable amount of
fuel on the take-off, but not so great that it would effectively double your
take-off run.