You're right - any of the bespoke dinky fitted solutions like Fazua and ebikemotion are going to be 'back to the bike shop/manufacturer' for any fixes. They're effectively closed systems.When it comes to problems and ease/cost of fixing I suspect that the Fazua will probably be just as bad as the Bosch. I don't have any strong evidence for that; the Fazua hasn't been around long enough for evidence to build up. Just a feeling that kind of propriety system might well have issues.
Thanks - we have a tandem with a Cytronex system so not "do it yourself" but that aside we find it ideal and used in the same way.I must admit that I’m tempted by Fazua based bikes but when I weigh things up I really don’t think I can improve on the solution I currently have. Decent steel tourer fitted with a lightweight rear hub hub motor. I have quite a big battery in a frame bag, because I sometimes want to go long distances. The only thing I might change is perhaps having two smaller batteries instead of one big one, this would save about 1kg when riding day to day. If anything were to go wrong, all parts are easily fixable or replaceable.