While playing with my new 20b, I noticed something odd about the days between dates calculation. Try this and see what you get:
Date 1: 6.252003
Date 2: 12.312010
Actual days: 2746
Now switch to cal 360 and evaluate: -721,255 is what it shows on mine.
However, on both the 17BII+silver and 12c 25th ann. ed. the same calculations give these answers:
17BII+: Acutal days 2746
360 days 2706
12c: 2746
after pressing x<>y swap button it gives 2706