Are manufacturers starting to make such things harder?
I ask because my neighbour was telling me about a local outfit running Euro 6 Daf's who were needing it deleted (not a legal requirement here apparently) but the dealer said it couldn't be as easily done as Euro 5's as a normal remap wouldn't work?
What happens to these maps when the dealer plugs in to the machine?
Dealers don't really know what they're talking about, the eastern European code crackers are always going to be one step ahead. A Euro 6 DAF is probably just running a Bosch EDC7 so I don't see why it would be an issue?
If they plug in to read/clear codes, they won't find anything out of the ordinary. If the dealer updates the ECM/PCM software, the map will often be erased. If parts of your Ad Blue/DPF/whatever system have been physically removed/disabled, you'd end up with a fault code and often an engine in limp mode.
Best to stay away from the dealer.