Hi Jodie,
I live in Australia, there's only a couple of hours time difference between us...
The 500 also has 18 Velosity Pads, the 50 has none...
As I said, I don't think the 500 was around when I bought the 50, but it may have been...
If you think the extra features will be of value to you go for the 500... I'm very satisfied with the 50, it fulfills my requirements at the moment...
Cheers, Bj ( :