I have that exact remote stalk already.
It comes with many of the new Sony head units including mine, which is the Sony CDX-M770. I just verified the part number on mine (easy to do as it is sitting here next to me since I didn't actually install it - read below).
Anyway, here is what I have to say about it:
a) It is indeed IR. A unique feature is that the direction of the IR LED can be adjusted over a 60 degree or so range by an external thumbwheel. The only thing is that the IR LED is at the base of the stalk and seems to be mounted parallel to the mounting plane of the remote, and the available adjustment lets the LED's effective direction pivot around the vertical axis of the remote.
b) It sucks for my application! I used to have a wired remote with my last Sony head, and had mounted the stalk in the center console between the seats... which turned out to be a very nice location. Due to the IR interface and LED location/orientation, the new stalk won't work there (blocked by shifter, etc). In fact, I tried locating the remote in many places in my Honda CRX, and the few the worked were not really that much better than just using the front panel or regular IR remote (which also comes with the player I have).
I would recommend sticking with the wired ones, unless you have a place you want to mount a stalk such that the base of the stalk would have a direct line of sight to your head.... As a note, I did find that interior reflections allowed it to work in some unexpected locations as well, but not usually as reliably.
In addition, making it work with the EMPEG may or may not be another issue due to the IR interface.