Here are the two ejectors, original Gen4 and the 9/2011 update. Mine does not have a part number on it.
The word is that this part addresses the erratic ejection issue by catching more of the shell casing. Changes to the Gen4 frame introduced a small amount of flex that caused the original Gen4 ejector to sometimes miss the "sweet spot" on the shell casing as the action recoiled. Increasing the size of the ejector face should increase the likelihood of an effective strike on the shell case.
Attachment 154
The new RSA was reinforced to address an issue found in a few Law Enforcement agency Gen4 pistols where the head of the recoil spring assembly broke due to a change in the manufacturing process. If you look closely, you'll see the only change is the beefed up head plug and a new capture ring that surrounds the end of the spring.
Attachment 155