I have a 2007 S4R Testastetta. When i got it, the tank was badly swelled and deformed. I put in a claim to Ducati NA, which they denied due to beinfg out of warrenty, and outside the terms of the class action lawsuit.
I purchased a new tank, and I've been very particular with fuel, ONLY using non ethanol. It's sometimes difficult, as i get 80-100 miles a tank, which is a bit less than I'd like, but i have a non ethanol station a mile from my house, so it isn't hard to fuel up.
That said, when i discussed this with Ducati NA (when i bought the new tank), Here is what they said to me:
"Ethanol Phase separation and bike storage:
It has been Ducati’s goal to use to choose the best product for a particular purpose. Because of the extreme shape of the tank, plastic was chosen. We have found through extensive testing, tank expansion is not an issue when fuel is run through the system regularly. Ethanol blended fuels have a short shelf life. When fuel sits, ethanol separates from the petroleum base (Phase Separation). The separated ethanol can cause multiple issues; like clogging fuel injectors, fuel level sender accuracy, and expansion in plastic tanks. If you live in area where you are unable to ride year round, following standard cold weather storage procedures recommended for all motorcycles will alleviate ethanol separation. Below you will find an article explaining life expectancy and the separation process
http://www.fuel-testers.com/expiration_of_ethanol_gas.html
On page 67 of your Owner’s Manual, Ducati recommends draining the tank for storage.You may find in general motorcycle storage articles that recommend adding a fuel stabilizer additive to combat the separation process in ethanol blended fuels."
So...long and short of it: IF you use ethanol gas, ride it often, burn up tank fulls quickly, and don't let the gas sit in the tank more than a week or two. Thats not hard for me during riding season, and in the winter, I make sure that I drain the tank. And besides, i use the non ethanol
Hope that helps.
David