Here is what I did to make it work after 20+ unsuccesfull attempts:
1)backup, ##786#, wipe-reset
2)after reset shuts down the phone didn't let it come up again and took the battery out
3)put it back in and boot in bootloader
4)wipe, wipe cache
5) Flashed the latest 3.0 OMJ ROM (I don't think this step matters but i'm putting it here for consitency)
6)reboot, follow update screens, check PRI version and it's 1.4 from the first attempt
I didn't invent this, somebody mentioned this already but without details.
After that the data speed became really sloooow (about 100kbs each way). So
7)settings->system-update->update profile
and my speed now is back to the crapy 0.7-0.9Mbps at home as it was before - no noticable improvement
I think step 4 is the one that makes a difference - perhaps ##Data# does not clean cache properly