Is there any newer release than 4.03.SP2 ?
No, not yet.
Also which is the best unlock method to date? Any light there?
Hasn't changed; go to the
Riglol 1.03d website, enter your unit's S/N, and the code
DSER in the
Options field (leave
Privatekey blank), then hit the
Generate button. A small window pops up with your unlock code.
At this point, RTFM on how you enter this code and do so. Then reboot IIRC, and you're done.
Don't sweat over this, it's very easy to do.