[Redmi 1 4GB] Is it Safe to Update to MIUI 7 ?

Hello,

I use Redmi 4GB that comes with MIUI 5 SG, then I update it to JHBMIBF19.0.
I'm thinking to update it to MIUI 7 5.8.10 developer rom.
I wonder if it safe to upgrade from MIUI 5 to MIUI 7 on my Redmi 4GB.
Cause I'm afraid that my Redmi 4GB will

• Ran out of memory. Currently, my Redmi 4GB already consume 90% of internal memory, and my applications isn't consume that much as I check on App2SD. Since I update to JHBMIBF19.0, it used 90% of internal memory instead of 20% when on MIUI 5 SG.


• Slows down / lag. My current MIUI 5 had some lag when launching Instagram or BBM, it can took very long and sometimes not responding.


• Some application may break. Some said that after updating, their google play didn't work, and many apps didn't work.


• Some hardware may break. Some said that after updating, bluetooth, wifi, or many hardware wont work.

If I backup all my app data to my PC with MI Phone suite, can I get back once I update to MIUI 7 ?

So, anyone who updated their Redmi 4GB to MIUI 7, is safe at all ? no problem / bug ?
And how to do the update, should I follow Xiaomi's flashing guide that use Updater > Select Installation file ? or Reboot to recovery mode then Wipe / reset and then install update.zip?

thanks.