Thanks for all the good input. I was figuring there might be a little incremental savings over the Superflo VS, but not that much, given that the Superflo VS would already be a lot more energy efficient than the existing single speed pump. My general impression is that the Intelliflo is just a higher end better pump and having more HP is a good thing for efficiency and equipment lasting longer, etc.Not familiar with the Superflo, but I have found the Intelliflo to be an excellent product. I'm not certain about this but I think the Intelliflo might be a little bit more energy-efficient at lower speeds.
The Intelliflo uses a permanent-magnet motor, whereas the Superflo appears to use a standard AC induction motor. PM motors tend to use a little bit less power because there is no current required to magnetize the windings. The tradeoff is that the drive electronics (the Variable Speed controller) generally needs to be more sophisticated for PM motors.
In my opinion, the $300 difference will buy you a superior product but it may not reduce your energy usage by a huge amount. The major benefit, in my opinion, is that the Intelliflow has a motor that is rated for something like 3+ HP. Since your pool only needs ~ 0.5 hp for filtration, the Intelliflo will be quite a bit oversized for your needs. In this case, the oversizing is a very good thing, because it means that the motor will be running quite a bit cooler than a 1HP motor. When it comes to motors, the power rating is largely a function of how quickly the motor can cool itself.
The Intelliflo will also have more capabilities if you ever choose to install an automation system in the future.