Some thoughts...
When it's successful, the Ross Procedure is the best of all worlds. No wearouts, no meds. Hands down the best.
The quandary is that when the Ross is being used for someone with a bicuspid valve, it's extremely difficult to determine whether they are at risk of developing connective tissue disorders over time that will damage the valve's usefulness. Those tissue disorders are often hand-in-hand with the bicuspid valve, but they don't always manifest themselves during the person's lifetime. What can happen is that the tissue in the valve becomes mixomatous (connective tissue is replaced by fibers and other, less capable tissues) and the once-pulmonary-now-aortic valve begins to leak, and eventually needs to be replaced. One special caveat: if the pulmonary is bicuspid, don't go with the Ross. That seems to decrease your odds of long-term success. Ask to go to your backup valve if that happens (yes, you should have a backup plan [and valve choice] in place, in case things aren't working out in the OR). One of the reasons the Ross is not as popular as it was is because it was done too often without proper concern given to that issue.
Surrounding tissues can also become problematic, causing more leakage and perhaps involving the mitral valve. Then, if that's replaced, you have three surgical spots in your heart.
Does this happen to everyone with a Ross? Certainly not, but there's a certain amount of crystal ball work involved in determining if it will happen to you, personally. Dr. Stelzer is certainly as good as any human can be at making that determination and of course, doing the operation itself. He is one of a handful of very top-shelf Ross Procedure surgeons.
You might still get an expanding aorta, but if the valve is still good, it can be spared with a modified David procedure, which keeps the valve in place while dealing with the aorta.
If you get a replacement pulmonary valve from a human donor, you will have a "crisis" point with it (apparently a rejection reaction), but once it passes, the pulmonary usually continues to function well. Paradoxically, I've read that the worse that crisi is, the better the replacement pulmonary valve works later. I know that pulmonay valves have been replaced via catheter, so there are new possibilities for the pulmonary piece working out nearly 100% of the time, one way or another.
For that matter, having the formerly-pulmonary-now-aortic valve fail some time after a Ross procedure would not make it impossible to replace via catheter, should you be quite old by then, or your body not be able to deal with more conventional surgery.
Best wishes,