The day after Chorus started installing fibre into our street, my VDSL modem resynched with these stats (previously 46Mbps/8Mbps). My current working theory is that it's becoming increasingly nervous about its ongoing role in our household, and is trying a last ditch attempt to prove to us that it can still be useful :-)
Looks like you have actually just moved to 6dB, lower snr = higher speed.
Those tweaking their snr and noticing an interleaving increase, this is to be expected. Interleavings is a method of reducing errors.
ddDLM Does appear to favor speed over interleavings with these changes.
There was mention of interleavings possibly being switchable on VDSL with the new changes, although this has not been confirmed. Is implied by the official documents released.