My exeo hasnt been done, but my Leon has (before I got it) and within about 5000 miles of it being done the EGR valve has failed. Luckly the car was still under warranty from the supplying dealer and they agreed to cover the costs (£700+ inc fitting).
when asked if it was due to the "fix" the official line is no... but some EGRS may have a few issues to now opening wider and entering areas of travel which have not been used bore, and therefore carbon build up may cause some problems.
The dealer then told me they were on back order due to the amount which have failed... so read into that what you will.
On the other hand the Leon is still doing good MPG, but the Regen is a pain, as part of the fix is shorter but more open ReGens. (The idea being that before it would wait until the DPF is basically full to burting before doing a regen. this then take a while do - say 15 mins for arguments sake, and if it does not complete the regen in time then there is no long until another is needed, or it forces it around town.
The high temps for longer periods of time are also not good for the substrate within the DPF and the wash coat on the cat which is in the same housing as the DPF.
The new idea is regen say twice as often, so when the DPF is only half full, but now it only takes 5 mins to complete, meaning it is more likely to finish, and because the high temps are not present for as long it des not do as much damage to the cat.
Mine however does seem to keep doing regens around town randomly, which all my others before the fix never did - The exeo will though, it loves a random regen round town.