On a Dry Runway, cross wind limits are:
ATR: 35 kts
Q400: 32 kts
On a wet runway:
ATR: 28 kts
Q400: 32 kts
So ATR wins on dry, Q400 wins on wet, overall, they're about the same.
Why did the dash operate today? Hard to tell, I can only assume the runway was wet or there were other limiting factors to consider.