Read your post above and decided to test my Logitech Ultimate IR blaster with a 3.5 stereo extension cable using 3.5 mm / 2.5 mm stereo adapters on each end. Initially the signaling did not work when I positioned the IR blaster several feet away, however, after placing it closer to the W900a (right under the IR receiver and a few feet away as well), the TV started to receive the signals no problem. Maybe using an extension cord attenuates the signal? I have no idea but needless to say I was a little worried seeing your post and how I wanted to wall mount this set having one of the Harmony's IR blasters wired out to it as well.
And FWIW, I tested this set against a Samsung F8500 plasma as well. F8500 has superior blacks but a tight vertical viewing angle for those mounting the TV in an elevated position. F8500 is pretty bright but doesn't get quite the bright white output of the Sony.