hi guys, am back!
ok, some piece of insider info. the k750i and the w800i are same wid some difference in the software. this is the reason why you can safely flash a k750i wid w800i firmware (this has been tried and tested successfully!)
so, the w800i is nothing but a rebadged version of k750i wid some cosmetic changes (like the walkman button, cam cover etc.) and 512mb memory stick duo.