Some update from my side -
When I flashed the RUU in this thread, I was facing many issues e.g.: launcher used to get hung for long period of time, back key did not work reliably etc.
Then I found out that, the RUU in this thread has version: 4.05.401.1. But the Viper and TrickDroid etc are using version: 4.06.401.1. So I decided to first flash the RUU to get 4.05.401.1 and then without reboot just flash the firmware for 4.06.401.1.
The steps I followed are as below -
0. BACKUP THE WHOLE SD-CARD (since it is erased due to upgrade in hboot version and/or partition scheme changes)
1. Put the phone into fastboot mode
sudo ./adb reboot-bootloader
2. Ensure PC is able to detect the phone in fastboot mode
sudo ./fastboot devices
3. Start the RUU mode
sudo ./fastboot oem rebootRUU
4. Flash the rom.zip corresponding to RUU for version 4.05.401.1
sudo ./fastboot flash zip rom_4.05.401.1.zip
5. When there is pre-flush error, issue the same command in (4) again
6. Once the flashing completes, do not reboot the phone
7. Flash the firmware.zip corresponding to RUU for version 4.06.401.1. You can find it on this forum, please search.
sudo ./fastboot flash zip firmware_4.06.401.1.zip
8. Erase the cache
sudo ./fastboot erase cache
9. Reboot the phone
sudo ./fastboot reboot
With these steps, I am not seeing the issues I mentioned previously. The battery life is also good (i.e.: sufficient for me).
I thought of sharing this info here so that others could try it (on their risk, of course !!). Hit the thanks button if it helped you.
I used Linux machine for playing with my phone. I have folder called "bin" in my home folder which has the binaries for "fastboot" and "adb" in it. This "bin" folder is also added into the "PATH" enviornment variable for shell. Please adjust the paths according to your enviornment.