See below, hoping I don't have to buy discs as £200+ is steep at the moment... There does not seem to be much ridge between the friction area and the inside lip. No ridge at all on the out side.

I can measure up with a calliper if anyone has the wear specs.

Much larger size here http://i.imgur.com/m6eQ4LH.jpg

** Measured at 4.72 so I guess that is good still, seen 3.5 and 4.5 as the limit. Still not sure which is correct though

I think with a bit of emery cloth they will be fine.
The limit is normally stamped on the disc somewhere.

appearance doesnt make much difference as long as there is no deep ridging or anything else that will interefere with the way the pads use the disc. Often some smal stoes or soething trapped in the pads can cause small ridges, just clean eeverything down with brake clener and with some use they will shine up again.

Important thing is to the chek the overall thickness in several places against what is stamped on the disc. Do not go by the service book but rather the discs themselves as it will be stamped on them.

Depending on disc the thickness can be different.