I have followed this thread with interest and have the following comments. All plate diffs will wear during normal cornering ie road use when both wheels have grip the diff will only lock when grip is lost to either wheel. In terms of durability I have run with ZF plate diffs in all my sevens since 1997 and clocked up over 70,000 miles with lots of track time 10 years ago I have only twice needed to have my diff overhauled, once the plates were turned over and re-used , the other the plates were replaced. I think its fair to say that the ZF plate diff has proved itself as very durable, I also know several other owners who have run with the Quaiffe ATB units and once again these have been bombproof its only weakness being shock loading coming off curbs, easy to be sympathetic and avoid this. My other observation is that I do not agree with others who have said that there is no difference between the Ford and the BMW casings, the Ford is cast Aluminium and the BMW is cast Iron, they both have quite different coefficients of expansion, its been my experience that when pushing hard on track with the Ford the case expands more than the Diff cartridge and this takes a lot of the side thrust off the bearings that locate it. result the diff becomes very noisy and transmission backlash increases. The BMW should be more stable in this respect. I am sorry that I have no experience of the Titan but would say that there are a lot of happy owners out there that have had not trouble with their diffs, it must be very worrying for owners to hear stories from a handful of owners of failed units but this needs to be put into context of actual numbers, and also keep an eye on the static preload, swopping to the more durable sintered plates when preload gets below 20 lbft. I have been given advise on lubricants by well known Caterham transmission specialists but found Castrol Hypoy LS has worked better than anything in my diffs. I consider some of the new GL5 too slippery.