Dell Inspiron 15R N5110 Windows 8.1 upgrade

Hello Dell Experts,

I'm planning to upgrade my DELL N5110 laptop from Windows 7 64 to Windows 8.1 64. Laptop is very crucial entity as my whole development work is depends on this stuff.. I surfed few threads here and observed lot of people had problem w.r.t Win8.1 after/during upgrade process.. 

Could someone provide clarification on below queries ?

- Late 2012, I heard Win8.1 is not tested against N5110/15R series laptop's . Is it still the same outcome or tested ?

- Any assured/promised work(able) drivers available for Win8.1 ?

- I 've CISCO VPN software which is said to be compatible with Win8.1 but I'm not sure about after upgrade it is guaranteed to work as like now as work is totally depends on this software connection. 

The main reason for this upgrade plan is to save the battery life.. I had Win8 years before and felt battery life was good.. But due to the fact Win8.1 release and free upgrade my system got crashed  after Win8.1 upgrade and with help of Dell Executive (time period when I had warranty alive) I managed to go back to Win7. 

Kindly let me know your view on this regard. 

Thanks in Advance.