No racer here just a rec guy.
On my old X2 I had a set of plastic sponsons made by Samora's Ski Perormance. Well it did make it turn a heck of a lot sharper. I have debated on buying some JSU or R&D 800 SXR sponsons for my current X2. Just got to thinking I could have one X2 for free ride with tubbies/shortened hull and the other set up more liek a racer.
It all depends on what you want to do. They will help your X2 turn sharper about as much as a top loader helps you.