Ugh, there was me thinking it was just the NTP on our playout machines going squiffy.
The delay does to some extent depend on the state of the receiver and signal strength - we've got two in our rack (one as a backup) and they're frequently a second or so out from each other.
We were recommended 120cm dish by IRN (in East Kent) ... like we can afford something like that! And next 80cm or 66cm. We currently have two 53cm dishes. They're rubbish, and we totally loose signal if it rains.