The new license looks acceptable to me, but you should make sure your code matches what's in WebRTC.
There may also be some technical benefits: First, the IETF version was slow. I heard rumors that better implementations exist. Perhaps GIPS released an improved version. Second, the IETF version allows the implementor to choose a frame size. That was fixed at compilation and caused an issue with Sipphone, for example. WebRTC probably standardized the frame size.
The license I sent earlier doesn't seem to be available on the iLBC website any longer.
GIPS was acquired by Google in 2010.