I backed this one recently because they were set to reach their 2nd stretch goal, a twist throttle (a progress update today confirmed they have blown way past it).
I've used the
Commuter Booster (CB) beta friction drive kit that ceased development, so had in mind what I liked and wanted in a friction drive kit. It was light weight, minimal battery voltage meant more capacity for less size. Using it on a fast/efficient pedal bicycle meant keeping the nice feel of good wheels. Kit weight effectively a rider/water weight addition. Because the pedal bicycle was rewarding to ride like normal, I use the assist as an exception, also because it's noisy and not a nice bicycle experience full time.
The Add-E was nicely minimalist (nice machining and carbon fibre use), no wires above the unit/battery proximity, but pedelec friction drive constant on when not wanted is a negative. To turn it off required reaching down to twist the faux bottle battery cap. It was also a lot more expensive, and motor phase wires still exposed out of motor. The battery also can't be swapped/changed for an alternative as easily as the bottle has the electronics.
The OnWheel like the CB has programming and display features, but keeps minimalist with no fixed display with an wireless Android app, and the removable motor/housing keeps the phase wires tucked away.
Having the choice of pedelec or throttle is a deal maker for me, able to set your max power and speed on bike computer display for testing and remove it when set up means just a throttle wire up to the handlebar.
While the standard 8Ah battery is cheap/dated, the kit price is low and allows use of a lighter/compact 8Ah LiPo or higher capacity 6S 16Ah LiPo within a 750mL bidon footprint in the bottle cage mount, that I've already got and can use in series for a 48V kit, so economy of generic versatility.
With all the boxes ticked, fingers crossed that the huge crowd funding success leads to a nice product delivery. They are heading towards the $300k Euro mark like the Add-E, which to our dollar is approaching half a million? Pretty powerful lean development! Timing it at EuroBike must be worth a significant bonus too.