Seem like Stern and JJP may soon have their own range of after market mods for their tables, apparently:
W
http://pavlovpinball.com/official-mods-on-the-cards-at-stern-jjp/

Would that mean that Stern will revise their warranty coverage?
At the moment, the factory only covers CPU and DMDs and the sellers are lumbered with the rest. This idea to market mods might put more pressure on the sellers/distributors service and warranty coverage.
There may be even more grey areas in terms of user specific mods and warranty/service. I suppose the mod is OK if user installed it on a 12 month old machine and the mod does not affect other components in a bad way.