Roddy,
For the 155c units, US or International model, it is all the same software but this is not true for all units. Justin lists a “597” unit. There are different software downloads listed for the US versus International models, depending on which “597” model unit he actually has. We have made 597ci, 597ci HD and 597ci HD DI model units, so the US version software may not load in his unit at all.