Does anyone know anything about the sensitivity of control units for model railways? Old Hammant and Morgan units could take a fair bashing, both physically and power use wise. The newer units coming on line don't appear to be as robust.

I don't really understand what you mean. DCC, properly used is as robust as any other form of control. What make of control unit are you using

I have owned a lenz system for a few years and although it took a bit of getting used to I have never had a problem with it, Reading and understanding the manual is paramount with DCC. I have had few decoder failures. I have repaired and fitted decoders to a good number of locos for other people which had decoders fitted incorrectly which I have found is the main problem with DCC. Follow simple rules and you cannot go wrong, rule #1 is read the manual. DCC is more robust than it used to be. I can remember the days when a decoder could stop working if handled incorrectly but these days are long gone. DCC is the way forward.