i've converted my k750i to w800i, and was easy :D

desc ->
Detected SonyEricsson: K750/D750.
Phone Color RED
Flash ID: 200D
Status Ok, OTP Close, CID36, PAF1

i've used Davinci_13.7 with flashes:
W800_R1BC002_AMERICA2.RAR (Im from brazil)
W800_R1BC002_MAIN_EU_EMEA.bin
W800_R1BC002_FS_AMERICA2.bin

if you want i can send you the link files. :)
good lucky