It is hard to say if there will be a significant difference. You really have to compare the braking HP of each pump which is the service factor times the label HP. If they are close, there probably will be minimal difference. Your GE pump should have a service factor listed on the label. Usually older pumps have lower SF than newer pumps.

The MaxFlo pump is speced as an uprated pump which means that a 1.5 HP uprated pump is really a 1.0 HP full rated pump. So it is likely to be much less powerful than your current pump. In addition, the MaxFlo pumps, despite it's name, tend to be low head and low flow pumps. At 50 feet of head, this pump will only output about 50 GPM which is much too low for a spa.

I would stick with one of the high efficiency pumps such as the Hayward Northstar, Pentair Whisperflow or Sta-Rite MaxEPro. Even though these cost more money, over the life of the pump you will more than pay for the cost difference in electricity savings.