It is actually possible to remap the MSB ECU's by replacing the OTP chip with an equivalent reprogrammable chip. Obviously it requires different techniques to using Td5 Map Editor and a tool to reflash via OBD but it doesn't require an ECU replacement to achieve.
With the NNN ecus it's straight forward to create any bin you need using the Nanocom Map Wizard :
http://www.nanocom-diagnostics.com/down ... 613982.rarThere is a description of how the Nanocom .map format relates to the ECU .bin here:
http://www.discotd5.com/ecu-reverse-eng ... are-layoutThe .map format has a 9 byte header, and a 2 byte check sum surrounding the variant and fuel maps. The variant map starts at an offset of 0x9 and is 100kb long, and the fuel map starts at 0x19010 and is 16kb long. The "base ECU code" described in the above link is common to all NNN variants I've seen so pasting the variant and fuel maps into the correct location will give you a .bin you can use.
cheers
Paul