This is currently the longest time I've gone without a charge and so far real life battery consumption is line with expectations.

Although the battery measurements need to be re-calibrated. Currently it shows the battery losing the first 50% in a week or so but hangs on at over 50% for over a month. But even after calibration, the measurement accuracy would be dependent on too many factors anyway (battery capacity, temperature, make etc.). So the only take-away is that the battery consumption is accurately 1-2mA during usage.

The keyboard has been under moderate usage (8-12 hours) per day and is currently still going.