I just checked my exposures taken around 3 am on 25th Dec and 27th Dec. I'd estimate the comet has moved about 5 degrees in declination over the 48 hours - which is about 6.3 arc secs in declination per minute. Astroman did a great job of
capturing a closeup of the comet's head, and I had no problems with
stacking 301 sec subs taken at 14 mm focal length on an APS sized sensor.
Good luck - I look forward to seeing your results!