As an owner of 3 Sabres and a Fox, I think I can answer some of your post. Firstly you need to be really careful what you read on the internet as a lot of what's posted on Wikipedia is rubbish.
Al CVR hulls and turrets are constructed from welded plate. There is no casting, other than indiviual pieces like the mantlet. There is less material and less welds in a turret than a hull, therefore the hulls are much more expensive to produce.
136 Sabres were built, all have been disposed of. A lot went through Withams, the rest were cut up by ABRO. This was done in 2004, other than those which are restored and a few under going restoration, they are all gone.
Fox was not a sucessful vehicle in service, they are hard work to keep going and anything which needs repairing is not a simple job. It's much easier to do any job on a CVRT than it is on a Fox. If they had continued to use them without turrets, they would have had to get rid of them when swapping to diesel anyway. There is not a lot of room in the back of a Fox when it's complete.
Chris