Cost and competition. I have also heard that in EU, warranty service picks up at your door. The only thing I have ever bought in the US with this kind of service was my Dyson vacuum, and, of course, Dyson is a UK company.
I agree with the AOpen 1648 speeds. I also agree another burner would be a good use of the additional $25 cost over the AOpen. Add a BenQ 1640, or a Pioneer 109D and you will get something different. The BenQ 1620 seems best for +R; Pioneers generally seem to prefer -R.
You can never have too many burners, you know.