Just to add...
GL300B controller has a frequency range of
2404.00000000 - 2480.00000000 and a power output of 0.0380 watts
(Thats only about 1/40th of a watt)
GL300C controller has a frequency range of
2404.00000000 - 2470.00000000 and power output of 0.3030 watts
(Thats over 1/4 of a watt)
Going from 0.038 watts to 0.3030 watts a increase of 0.265 watts or 697.37%
W323A has a power output of 0.612 watts
W323B has a power output of 0.520 watts
going from 0.612 watts to 0.520 watts is a decrease of 0.092 or 15.03%
So perhaps they figured it was more efficient to increase the power output on the transmitter and slightly lower it on the bird.
After all the RC usually can be ran for much much longer then the bird and has more room for battery usage.
To add even more:
I recently had the opportunity to have both a W323A with a GL300B and a W323B with a GL300C.
I was able to test a few things out...
Off the bat when using a Galaxy Tab S2 at a controlled distance on the same track using the same tablet.
I can say I concluded from that that the FPV looked better (smoother) from the W323B + GL300C.
So you say well perhaps it was a fluke during the testing. Well I did both tests again with the same results.
I then tested something similar but further away...
Again same track and distance for both but this time instead of going say 200FT with a height 180FT of away on the same track I went 1600FT away at a height of 300FT.
I basically went as far as it could under the same conditions until I saw "Weak transmission signal".
Again the FPV looked better on the W323B + GL300C vs the W323A + GL300B.
It did seem that the "weak transmission signal" started happening sooner with the GL300B + W323A but that could have been other factors that caused that.
Bottom line. People need to get it out of their head that the ONLY reason there was revision was to save money on manufacturing.
That could be the case for components as during the manufacturing process often manufacturers cut deals or change suppliers to get better deals.
This for one doesn't always mean less quality. (sometimes it does).
However in this case where DJI is trying to solidify itself as the leader in consumer drones I highly doubt their revisions were simply to make a product cheaper and worse.
They are not idiots and would be foolish to ignore any discovered issues etc.
Plus on top of that the same R&D department that develops things like the inspire or the Phantom 4 also is constantly looking at issues etc.
It also should be noted that on here and on the DJI forums there have been some radio and electronic experts that seem to feel that the changes in the frequencies and power outputs are very negligible and would not have a major impact at all. However if everyone wants to go strictly by numbers and not by advice etc then clearly the numbers speak for themselves.
Just saying..