Here are a number of photos showing the differences between the old oil/water pump and the newer one. This change started sometime in production year 2011. So many 2011 models that were actually made in 2010 and early 2011 have the older unit. This change started with motor number 483015.
The main differences are a redesigned water pump impeller and oil pump that can fill from both sides of the rotor.
Triumph has never come out and clearly stated the reasons for the change but based on racing issues and unofficial comments the changes were to reduce cavitation and sustained high rpms and to increase flow overall. The oil pump is what they call a dual fill in the new unit which means oil is pulled into the pump body and fills the cavity where the rotor is on both sides of the rotor rather then just on one side. Also the water pump on the new unit is a conical shaped case unit rather then a stamped sheet metal one. Both changes would appear to improve flow.
Should you replace your pump with the newer one? If you are on the track a lot I would recommend it. If you are simply street riding and mostly commuting or touring then it's not necessary but would certainly wouldn't hurt and is relatively inexpensive if you do it yourself. You can find these pumps on ebay for less then $40 but you have to know what you are looking for as the sellers don't know there was a change. As well as the pump you will also need the oil pump fill pipe which is the outlet pipe of the pump. Where this pipe attaches to the pump is much larger on the newer unit and the pipe was changed to suit. I haven't seen the new pipe used yet but I'm sure they are out there. New they run around $60. Use the photos as reference of what to look for.
I'll post a how to on the pump change with part numbers once I'm done with the change. I'm stuck right now without the fill pipe.
In all of these photos the new unit is on the left.
In addition to my photos here's a post by Samwise with photos of the internals of the new pump.
Here is a link to a post I made detailing the installation process.
The first four photos show exterior changes. As you can see the changes are more then just internal the unit is completely difference inside and out.
This photo is of the new unit specifically looking into the inlet side of the oil pump. You can see it feeds directly into the oil pump rotor. You can't see it clearly in the photo but oil can fill from both sides of this rotor rather then just one side like on the old one.
This photo is of the old unit also looking into the inlet side of the oil pump. You can't see the rotor at all in this unit and the oil can oil can fill from one side of the rotor.
Here's the new and old fill pipe. The top one is the new one in each of these photos.