No harm in trying it. You can always donwgrade back to the version you have currently.
It did very little for me as there is still no manual control like the older T models offered per system.
In fact the same settings that this firmware claims to have added already existed in the previous versions. They may have done some tweaking to how the unit responds to the hidden menu items as many do report better P25 decoding of simulcast sites.
In my case, I need a P25 setting of 5 and even with the new FW, I cannot set it that low plus it affects ALL systems so when I set it so my local system sounds the best, I can't switch to say one of the Starcom sites I can receive without first going into the hidden menu and setting the settings back to the recommended or default values first so I can get to a P25 level of 11 or 12 that works best for Starcom.
I was really expecting this firmware to restore the manual control that was taken away when the XT series were released but it does not.
I think each situation is different though as no two users have the exact same conditions and equipment so the only way you will know is to try the FW update.
If anyone says you cannot donwgrade, that is wrong.
I've had to remove this upgrade on both my 996XT and 396XT for testing purposes. Downgrading is as simple as upgrading but I'd first do a full radio backup of all your systems and settings no matter which direction you go as I have read reports where users claim to have lost systems and/or settings after the update.
If you are having reception or decode issues now with the Starcom sites near you, try the latest FW is my suggestion. If it does not help or makes things worse, downgrade back to the version you are running now. It only takes a few minutes to do it.