Vertigo,
The other snag with some of the big busses is that the blighters refuse to slow down at all if there is a tailwind. That leads some crews to target V ref before 4 nms.
I accept that slowing at 9/10 miles to 160kts is too soon but an A-330 won't slow down on the glide if it has a 15kt tail wind. A lot of operators deal with that sitch on a regular basis especially when approaching airfields effected by a sea-breeze which after a few go-arounds tends to make them gun shy.
The crews may well be slowing to prevent themselves going round and obviously they should inform you first. Out of interest, how much of a buffer do you allow for stablisation problems?
Ghost