We have a couple of Dahons and they work well enough. One issue with the Solowheel is that you need surplus amps to recharge (same as Torqeedo). Amps are precious on my boat, as we don't typically take a slip. Almost always on a mooring or on the hook.

Also, you can fix a bike using generic parts anywhere. Good luck finding a fix for Solowheel or Torqeedo when you're out cruising.