When does a VC need to be replaced?

This matter comes up on a regular basis and I had an  email in the last week about it.  An aggressive VC is not necessarily a bad thing.  Following is the reply that I sent to the last enquirer.
There are varying degrees of 'going hard', and it is not always detrimental.  As the VC becomes more aggressive, it becomes noticeable when doing full lock turns on a grippy surface - like dry bitumen - and very noticeable in tight supermarket carparks.  In these circumstances, it pays to use the minimum speed possible to reduce the load on the whole driveline.
I have found that an aggressive VC actually improves cornering and braking grip.  A further side benefit of this is helping to distribute braking forces, particularly on wet roads, and giving an anti lock effect.
The ideal solution is to fit a decoupler, which allows you to decouple the drive to the front diff when parking but otherwise run full time in all wheel drive.
The question is: just how "hard" is your VC and what detrimental effects is it causing?  In other words, how necessary is it to replace your VC?
----- Original Message -----
Sent: Tuesday, March 18, 2008 10:27 AM
Subject: [Syncro_T3_Australia] Re: Where to get a New VC?

I am a new member also and have a 89 trakka camper syncro with a VC
which is starting to show signs of locking. I would like to know if
there is a source of rebuilt VC's in australia. There is a lot of
information about them, and the problem of the liquid ageing, on
american Vanagon forums. I found a supplier in Belgium called busman,
the website is www.busman.be/ but I would prefer to deal with an
australian supplier if there is one. I would like to purchase one so
I can replace mine before it causes any damage.