1,000 km update - chain drop issues resolved, everything going great. Changed phaserunner settings to 96a phase current and 50ms upramp-little more brisk. Set CA peak to 40a. Motor hasn't been above 78 degrees even on long steep hills so the ferrofluid is working.
Chain drop resolved by changing to a FSA DH 42t chainring, adding a blackspire einfach guide and a sram gx2.1 10speed clutched rd. This has a different pull ratio so I've ordered an ultegra friction shifter like a TT bike has and Paul thumbies.
Had a nail or pop rivet shaft in my rear tyre but when I removed it the slime tube resealed itself and seems to be all good, touch wood. It definitely prevented a flat when it happened as it went through the crazy bob tuffy tyre liner and thick slime tube.