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.
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Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.