I'm with you on the Cyclotricity kit. Fitted two on to our Thorn Tours a year or so ago. Now just fitting two of their units on to Giant Stance full suss bikes. Just testing mine this morning and it rides like a dream, floats along.
Could say we got there in the end! Started with purpose built e bike after a bad accident to help recovery, then decided to convert our other bikes, the Thorns. Still not quite right, uncomfortable at times, as accident included breaking back in a number of places. So, one stage further, look at and try full suss bikes, yup could be the answer. Bought two from Pedalon and ordered two of the 500w rear wheel units, and, bingo, perfect. Can really recommend both bikes and kits.