Mine was wobbling quite badly when braking from around 70mph to around 50mph, though it behaved OK when braking at lower speeds.
I changed front discs and pads, and used original Vx items as advised.
I also had a slight play in the front wheel bearings so they were replaced as well while the discs were off (again original Vx).
After fitting new discs, pads, and bearings I took the car for a test drive and it stops perfectly balanced with no wobble at all. Done around 300 miles since and the car is still fine.
Can't be 100% sure if changing the bearings or changing the discs is what solved the problem, but on the balance of probabilities it was probably the discs.
Incidentally, the previous discs were also original Vx, done about 30k, and visually looked good i.e. fairly even and with small lip. So I guess you can't judge discs by their looks alone...
I am quite impressed with the new discs, they have good bite and what is most impressive is the total lack of any sense of drama no matter how hard I brake - the car just stops in its tracks, very efficient and civilized... no wobble, judder, pull, squeal or screech...
As for the wheel balancing, the weights are meant to compensate for imperfections in the tyre, not the wheel... (otherwise the wheels would have fixed weights that never needed re-balancing...). So if you are concerned then change tyres....