Drone - Bormatec Maja - EKF disabled from factory, firmware update?

Hello,

I have a Bormatec - Maja Drone. It is a commercial plane of 2mts span with pixhawk included. It is a RTF version with pixhawk.

I bought it last year (2015) and it arrived with Firmware 3.4

I found that EKF was disabled from factory->

AHRS_EKF_USE,0

I’m not sure if enable it or no, is there any recommendation?

Also is if it is recommended to upgrade the firmware to latest version. I saw some users showing some disconformities in the forum regarding the latest version.