Can anyone install a swytch kit?

On a Brompton, with the nut not fully engaging on the axles to provide sufficient purchase for the torque of the motors.

Yeah basically. I found their exact mistake and pointed it out to them politely, then when they decided to be twats about it (customers purchase not mine) I made an example out of them. Posted it everywhere, and caused some noise.
They took it back later that month, full credit 'in good faith' apparently.

Since seen a few of those kits on bromptons and they have the right length of axle and more appropriate fastners*

*However, as edscoble says, the forks aren't upto it thats why Brompton themselves own fwd motor jobs use a much stockier fork (TIG/MIG welded instead of brazed/lug style) to deal with the loads.

On a REGULAR bike, I think the swtcyh kits are OK, the quality of the parts/electronics/battery/connections/instructions are decent, make the asking price sound about right. Just not on a folder or anything weird.

Their customer service is basically two spotty teenagers grappling with crazy demand and no real engineering grip on what they are dealing with.