Just upgraded from WKM to A2. and Do I have to upgrade my Remove controller?
I am using Futaba T8fg Super at the moment, after I open extra channels and pair with A2. I will have 12 channels I think.
is that 12 channel are enough for A2 with S900 I am using GH4 gimbal.
Do I need upgrade to 14FG?

Thank you

While you would be opening channels on the receiver, it would not do the same on the transmitter. This would require for you to upgrade your RC in order to take advantage of the extra channels on the receiver (if your receiver is still compatible with the 14FG).