[a_k_s_h_a_y]

^^^ after flashing i am unsure(not sure) if your phone will start of not !!
you better go for a permanent unlock and then flash it ! so its going to cost you a bit more !

i don't know about unlocking coz i hv never come across such phones !
rest or other wise phone is very good .. nice music too .. you need good earphones

and M2 card is pretty costly .. that's a disadvantage .. !

the problems is after changes some changes take place in GDFS area .. so may be writing back original GDFS might slove it after having flashed to w610i .. and this i have not tested .. coz i can't as i don't have a locked phone anywhere in my country

i think by using TMS and unlocking cable you can permeanently fix it off