To the OP and others ready to jump into the eBike game…..
Roads generally aren’t all flat and straight. Earlier in this thread I stated that “You will work harder riding a 500 watt hub bike than a 350 watt mid-drive.”
Electric motors need to spin, laboring a motor at low rpm will generate heat. An extended work load, and especially lugging, can create enough heat to burn the windings which will lead to internal shorting. To ease the burden of the motor, manufacturers created geared hubs with an internal planetary reduction. By itself, though, that ratio is not enough to keep the motor happy under load. Because the hub is a fixed part of the wheel, to keep motor rpm in the safe no-heat zone a rider needs to keep the wheel rotating at a minimum speed. Under load, if a hub is rotated at less than 50% of its rated top speed, it will heat up. In spite of a hill's steepness, the rider still needs to maintain that minimum safe hub/wheel rotation speed. As the grade angle increases the rider’s only option is to shift to larger cogs in the rear cluster to reduce the work. That does lower the leg load but it also increases the crank’s rotational speed. Up a long and/or steep hill a continuous rapid spin can be quite arduous. Essentially, with a hub system you are there to 'assist the motor' while climbing, or it won’t assist you. The common work-around is to get a higher watt hub for more power. That will make a noticeable difference in boost, but bigger hubs have larger windings which contain more copper and add more weight. Larger windings are hungry and need large batteries which also add weight. Bigger motors also draw more current which will reduce the range per charge.
Similar to geared hubs, mid-drives also have primary internal gear reduction. Unlike hub-drives, though, a mid’s primary power is then routed to the bike’s rear cluster. That secondary reduction substantially reduces motor load so within normal riding parameters it never lugs or overheats. The mid rider isn’t enslaved to maintain a minimum road speed to keep the motor cool. Instead, a comfortable pedal cadence at any road speed is workable. The wider gearing range also allows the use of a smaller and lighter motor which can function with a lighter weight battery. Manufacturers don’t fit larger batteries to mid-drive bikes to feed hungry windings, it’s done to extend range.
Most of the pros and cons for both designs have been mentioned, so it’s up to the OP to choose a bike that fits his environment and preferred riding style. The routes I ride are quite hilly so my best choice was a mid-drive which lets me arrive at a destination without sweat-soaked clothing.
