Split off of this topic. JasonLion
Dittos to what scooperhsd stated, especially since both pumps you are looking at are 2-speed.
As long as you are in the market for a pump, I would at least look into multi-speed pumps and do some cost/benefit/payback analysis for your pool using local electric rates. The energy savings can be significant. I currently have a single-speed. When it comes time to replace it, I will only be looking at 2-speed and multi-speed pumps.
I hesitate to post hard numbers mainly because there are variations from pool to pool including optional water features and also because someone will usually dispute specific numbers which may lead to confusion. However, since I can cite references, I will make an exception in this case. When you reduce a pool pump's speed to half (50%) of full speed, the kilowatts needed to run it are approximately 1/8 of what it takes compared to running it at full speed. To achieve the same water turnover rate, you need to run the pump for twice the amount of time at half-speed compared to full speed. Accounting for that increased run time at half-speed, your still only using 1/4 the kilowatts to get one turnover of water compared to running the pump at full speed.
With that said, the above numbers are obtained in controlled laboratory conditions where all other factors are held constant. As stated above, each pool (and its features) is different and "your mileage may vary." Based on my example above (running at 1/2 speed for twice as long), the actual energy used will be between 1/4 and 1/2 of the kilowatts under real-world conditions - still a significant savings either way.
Multi-speed pumps can offer even more speed flexibility and energy savings compared to 2-speed pumps, but you also need to consider the initial cost differential and factor that into your cost-benefit/payback analysis based on your electric rates.
Here are a couple of articles that explain the energy use factors in more detail:
http://www.swimming-pool-information.co ... pumps.html
http://www.articlecity.com/articles/hom ... 5162.shtml