ADO seem quite good on after sales, parts etc as do Fiido as you say. The Kristall definitely a non starter parts wise so ruled out.
Ive just found out that the latest A20 + has an upgraded front fork apparently much stiffer as well as the changes to the controller so should be an improvement ( changes highligted in attached photo) .As for current just trying to get the most bang for the buck I suppose but as you say that could be a literal bang with the cheap batteries on these things