The Superpump is an uprated pump with a service factor 1.0. The Tristar comes in two version, up rated and full rated. The full rated 3/4 HP has a service factor of 1.85 and the up rated version has a service factor of 1.25. BOTH versions of the Tristar are larger than the 1 HP Superpump so will move more water but also cost more to run. The full rated version of the Tristar is larger than the up rated version and will use the most energy as it is the largest of three pumps. The Superpump is actually a very efficient pump not because it was designed that way but simply because the total HP ( Label HP * Service Factor) is so small. In fact it is one of the smallest IG pumps on the market today.

Also, if your wet end is in good condition, you could just replace the motor with a two speed as the Superpump comes in two speed version.