warped discs.

[clarky]

How easy is it to fit new discs? Any problems caused by ABS?

[Burchy]

I don't think the ABS will have ant effect on disk wear or jnudder.

I had to replace the fronts on my Mk1 model.  Pretty easy.  I loosened the disk bolts while the bike was on the centre stand, then I loosened the caliper bolts and the axle
Next I put a scissor jack ander the sump and gently raised the front of the bike so that when the calipers were off and the axle out there was sufficient room to undo the disk bolts and work the disks off the wheel whithout actually removing the wheel completely from inside the mudguard.  Refitting was a straight reversal

The scissor jack makes manoeuvering the bike really easy and precise for getting the axle back in

[wildybeast]

Have you cleaned the disc bobbins.Can cause judder 

[BigAlan]

As above, rotate and clean bobbins monthly or even better weekly as I used to, get a nut and bolt through the holes and rotate with a spanner while spraying brake cleaner, sorted.

And no when fitting new disks just ensure all is clean and lock tight the bolts.

[doebag]

Before condemning the discs.
Check the bobbins
Check the pads are free in the caliper and not binding
Check the pad material is not contaminated

[O.C.]

All the above is very good advice

I clean the bobbins on mine about every month, it doesn't take long to do and is worth the small effort