I personally don't think the bailer is worth the money
On my bailer the flappy bit has come of, so it is basically just a hole to the bottom. The bailer works fine without the flappy bit the only problem is is that you have to push it in hard to stop water coming in if you are not going quickly. It is fine if you put it in hard at the start of a race but the problem is if you want to pull it out after taking in water it can be difficult jamming it in properly later when empty.
This is not usually a problem for me as water never gets in the boat at my club as there are no waves. However when attending a regatta where there was waves, and sailing right through them (poor technique) and having water in, I had to open the bailer and it was difficult getting it back in.
They are a pain, but the springs are not legal. I believe the correct o-rings for the boat are #10 but i'm not 100% sure. You can get the whole set-up here, but unless you really need it I wouldn't advise it. http://www.optiparts.com/products/WDlaser.asp
One of the tricks to making the o-rings last a year or more is to leave the bailer closed when storing the boat. This takes most of the tension off the ring. The water will still drain from the cockpit if you just remove the rubber stopper...
The springs satisfy rule 26a in having the same function as rings.
O rings are not intended to be springs. They are compounded with carbon black for wear resistance. Bungee rubber and rubber bands are never black! Why live with something that is defective? As a comparison, would you accept a car where the window catch had to be replaced at least once a year??