The R449 E is an earlier regulator version and its Power component position in the schematic is different from the newer R449 F.
The only difference between the R449 F1 and R449 F2 is the soft-Start ramp and soft-recovery function, which has been removed from the R449 F2.
This difference is only on issue when the generator are started in parallel operation, due to the reactive current circulation during the speed slope before reaching the rated speed.
Those differences have no impact on the behaviour or the functionalities of the regulator. Therefore, it is not necessary to take any action to upgrade the version of the regulator.
In case of starting in // operation , our advice is to use a digital AVR version to enjoy newer functionalities such as better efficiency and remote monitoring.