I didn't know they had recently revised any estimates: there was a general revision (almost all downwards) a few months ago.
A recent update to HG612 modem firmware appears to the the reason that quite a few people have had interleaving removed recently: it typically takes DLM a week or more after the upgrade to see the improvement as stable and remove interleaving. That could well be the reason for the ping improvement.
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.