Thats impressive, and I have nothing that really compares...but I will anyways.
In June, we played the last session of two interconnected campaigns, the first of which started in 1991. That lasted for about 6 years, with one charecter (and player) remaining through the whole thing, and another there for much of it. Then various people moved, and then I moved to Paris.... In 2005, started a new 3E campaign with new charecters. All the players had been in the old game, and the campaign was in another part of the same world.
Meanwhile, after about 18 months or so, we converted the old charecters and started an off again, on again, PbP with them.
And of course, the two converged. Though I did manage to surprise the players at least a little bit when things finally came together. The old charecters actually met the new ones for just one session on the City of Brass (or technically it was the Fire Node), and the very last session after that was actually the old charecters tying up some long dangling loose ends. This included Galen, that very first PC.
In the end all the charecters where about level 13. But they, and what they did, certainly felt epic. (if charecters had advanced in the 2E campaing like they did the 3E campaign, and we played recently like we used to, they would be at least level 30).