...However, the consequences of a succesful kotegaeshi on concrete or in a bar may be devastating.
Alberto your last line is interesting but I have to point out that 'devastating' would imply a consequence other than a broken or torn arm : non-aikidoka when "kotegaeshid"
do not hit the ground with their heads. (You can all argue that point, you're welcome.)
What would Ueshiba have done?
Stotted him in the throat with the bike. No, really.