Can't answer that one -- I haven't compared prices and cost of installation.

Any well sized multi-speed pump will save you a lot compared to a single speed run 24/7.

It won't save as much money comparing a 2 speed run 2 hours on HI and 22 on LOW with a single speed run 6 hours on HI.

HOWEVER, one of the big benefits of multi-speed pumps is that they are VERY quiet on low.