Thanks for all the responses. While there seems to be some discussion regarding the actual GPM I should be expecting and what the electricity savings would be -- it does seem to confirm that what I am seeing is not right.

From information on Jandy's reference sheet (http://www.jandy-downloads.com/pdfs/pumprefguide.pdf), my SHPM 2.5-2 should provide roughly 160 GPM at 40' of head (high speed using 11 amps), and 80 GPM at 10' of head (low speed using 4 amps). I have no idea what my head is, but those numbers seem like they might be consistent with each other for comparison (and follow Richard's comment). If the 4 amps vs. 11 amps (from the Jandy chart) seem right, it isn't quite the one-sixth Richard was talking about, but could still provide some energy savings to run twice as long on low speed. 27% savings from current usage I guess ((11 amps - 2 times as long * 4 amps) / 11 amps).

Jason