A new Sentinel picture of PIIS is available. I checked the actual rifts and didn't find any relevant lengthening or widening. Only a very little calving must have taken place this week (500m x 150m of ice is missing) close to the junction of PIIS and the SW tributary glacier at the same place where another calving event took place two weeks earlier.
I looked at three different features of PIIS and compared their NW-ward drift between Jan 27 and Feb 16 (=20 days). The movement of the ice was 272m, 263m and 270m, respectively, which results in a speed of ~13-14 m/day, which is in the upper range of what has been calculated earlier.
The small rift in the SW tributary has moved north by about 36 m in the same time, which shows a much smaller speed (ca. 2 m/day).