Nerf Stryfe Dart Sensor - Updated Again?

When the Stryfe first came out, many people criticised its dart sensor tooth thingy, which although seemed like a good idea, blocking the trigger if it was not loaded, actually caused a lot more trouble, by jamming up the trigger frequently and not detecting darts loaded in non-Elite clips (mags).
This problem was rectified with a new dart sensor design, as showcased by BasicNerf's post here. The video, made by "Duke Wintermaul" on Youtube, shows that the new dart sensor is larger than the original, but could still be easily be attacked with, for example, pliers. The serial number for these Stryfes ended with an "a".
I picked up my Stryfe from Malaysia. Worried that this might be an original troublesome Stryfe, I took it back to the place I was staying at, threw in some batteries and sprayed off the 6 darts that came with the Stryfe. To my relief, they fired out very quickly, and the trigger didn't lock up. Noting that it was different to the Stryfes with a serial number ending in an 'a', I looked at the engraved serial number and noted it ended with a 'b'.