Three models, one mechanism. The only real questions are how far you go and whether you can get back to a charger.
Ridge — $749
800 W, 16 km of assisted climbing, fixed battery, 2,600 g.
Buy this if you are out for half a day and want to find out whether assistance is for you before committing to more.
Summit — $1,149
1000 W, 28 km, removable battery, 2,500 g.
Buy this if you hike full days. It is the one most people should own: full output, a swappable pack, and lighter than the entry model because the frame is better, not worse.
Summit Pro — $1,549
1000 W, 28 km × 2, hot-swap batteries, 2,550 g plus 480 g per spare.
Buy this if you sleep out. Hut to hut, multi-day traverses, field work with no power. If every trip ends back at the car, the second battery is money you could spend on boots.
Straight answer
Most people want Summit. Ridge is for testing the idea, Summit Pro is for people who already know they need the range.