The complaint about the Pace is the acceleration to 12 mph in the lowest assist when moving the pedals. That's an overly powerful assist. With the Ride1up 500, 700, and upcoming Core-5 shipments, this can be adjusted. So, whether you have 5 or 9 assist levels, that's an advantage, over the Aventon and Espin bikes, both. With the Ride1Up, it's optional if you want to use all 9 assist levels. You can configure modes for fewer assist levels and still adjust the power settings for those levels.
The 500 is a really nice bike, but I actually prefer the 700 over the 500 for the extra dough. The 700 has nicer wider 2.4" tires and will supposedly support 2.8", has a concealed battery, includes rack/fenders (in base price), has a higher capacity battery (as sold with bike). The only downside is that it's heavier, but then it has the higher capacity battery, rack/fenders, and wider tires, so that would be expected.