I don't understand why so many people are concerned with the superjet leaning in the water? If it rides fine, why are we worried about it?
Ignoring the lean is like ignoring a poorly tuned carb because it works "good enough".
Lateral imbalance makes the ski harder to carve. Right turns will be easier as the ski will naturally lean to the right. Left turns will be harder and will result in sliding because the ski will not lean well to the left and it take an over exaggerated riding position to compensate for even a small amount of imbalance low in the hull. Riding in a straight line in goofy stance will also be harder, as weight in the front right corner of the tray will cause a significant imbalance and loss of handling. A ski will handle vastly better if it is properly balanced laterally for the full length of the hull and good front/rear weight distribution.
You can get a lighter battery. I myself did not want to give up my slim Deka (lighter than the stock sized battery) for a expensive and poor performing lightweight battery. I opted for a 8lb lead weight between the two left mounts. The ski is properly balanced laterally now but I can still tell that the battery is forward of the lead weight. Never-the-less, my handling is vastly improved compared to when I had lean.
I myself have a recreation setup, that is to say, it's a surf / flatwater / race ski. The lead weight is an advantage for racing and better than going with an unreliable battery in the surf, but the extra weight is a hindrance in the flat water. If you were doing strictly flatwater, then I would say go with the battery, but in any of the above cases, I would take the extra weight over the imbalance.