Pumbaa, you have the right idea to make your own mind but trust that you will report your findings to the community. Given that I have worked on this project from conception, through design and construction phases and into the current manufacturing and type testing plan, I know 172s better than most.
To clear up a point, both the ROSCO specifications clearly identify the required maximum top speed is 100mph and 160kph for LM and Chiltern/LOROL units respectively. Chiltern and LOROLs ROSCO would never accept a poor relation sub class as it limits the future commercial viability of their unit; something the DfT still cannot grasp.
After reading this and other threads, I am amazed at the quantity of inaccuracies that are a product of the mis-reported top speed, for example, the remapping of the ZF Ecomat gearbox at Old Dalby. For clarity, the testing of the LM unit at Old Dalby is to dynamically validate design changes over the LOROL units, eg, Hubner leading gangways.
The purpose of raising this point is to correct perceptions for the benefit of wider community; take it or leave it, the community will find out eventually.
I have researched (a bit) and apparently the LM ones will be 100mph....
But why would the LOROL and Chiltern (London) units have "continental" specifications? Maybe it's to keep the specifications of the London Overground stock in line with the undergrond stock? Although that wouldn't explain why the Chiltern units also have there specifications.