pool newbie,
Some of the answer depends on your electric rate. If you go to the Pentair website, they have a pump calculator that will compare cost to run single speed vs. VS pumps.
I like the idea of a VS pump on the pool and spa with a separate fountain feature pump. Pentair makes a great controller to go with their VS pump. I have never been a big Hayward fan.
Most manufacturers offer 3 year warranties.
Good luck.

Thanks for your response. The Pentair website indeed shows that I can save a lot of $$$ with VS than single pump. However, I still don't fully understand how VS (2 speeds pump to be exact) works for both pool and spa. Can just one VS pump handle both spa and pool?

This post was edited by Pool_newbie on Wed, Oct 30, 13 at 10:35

Pool newbie,
A VS pump is not a 2-speed pump!
A VS pump can run from 400 rpm to 3450 rpm. you can dial in the flow you need. Example: you can set the pool at 1500 rpm and then when you use the spa you run the pump at 3450 rpm which should easily run 6-8 or more.
The important factor is to size the plumbing for the max flow of about 160 gpm for the spa.
The controller does the work after the set up. push the pool button and get the lower flow rate. Then hit the spa button and the controller tells the pump to move to 3450 rpm or whatever you have set.

Pool Newbie...the way the VS (variable speed) pump works for both the pool and the spa is that you cannot have both circulating at the same time. When the spa is on, the pool water is not circulating through the returns. No big deal. The spa is usually only on a small percentage of the time.