Been to it a couple of times, but not for last ten years, as usually clashes with something else -- or empty wallet syndrome lol.
There is another Biker weekend on Mersea at the end of the season, too, however, which I also sometimes go to, called the 'Condom Rally', although I believe the one held last October (the 30th Anniversary Rally), was the last one as the organisers are now nearly 70 and so are calling it a day and there is no new blood on the island to take it over.
Enjoy Italy. I've ridden to Vienna, Paris, Brussels (proper $h!te-hole) and Barcelona for rally weekends in the past, and so know you'll LOVE the experience.
I have also ridden comprehensively through the Lakes area between Austria and Italy, too, and it truly is breathtaking and beautiful, so see if you can factor a diversion in that direction into your trip, too.