As for the V scale compensating those at LTCC or SWanwick etc where the cost of living is higher and time to calidate is longer I dont see it as doing this. Firstly the V scale is paid on validation - which means those training at LTCC will on average be on the 15,000/16,000 salary longer than those going to airports who validate quicker.
It's not compensation as such more of a halfway house. If the V scale wasn't there, the pay gap would be a lot bigger as you'd go from T&D to the main scale. However, you can't wait until the guys off your course have all validated before you get any reward for validating and using your licence.
On the other hand, you could say that by extrapolating the "low pay to start for bigger future financial reward" arguement, those at regional airports should be paid full scale when they validate as their salary scales are ultimately lower than their peers at the bigger units.