The 0xb204 to 0xb206 update is not directly related to G.INP, but the 206 upgrades appeared to grind to a halt around the time of implementation of G.INP.
Its mostly bug fixes - see
this post@ron
Thats interesting about the update and 3dB coinciding at the same time.
I wasn't around when you reported that but I briefly read the post last week and didnt have anything further to say over what wombat already had said, and that at that time it did indeed look like you had a lower target margin but was limited to any full effect due to reaching 40Mb limit.
My sync is also too high to see any full benefits of a 3dB margin.
MDWS didnt capture the SNRm spike from me resyncing before FEXT disturbers, which is why I included the DSLstats graph.