[PolloLoco]

Actually - I just answered my own question and it's good news. If you hack the adapter that came with your phone - you DO retain headset AND headphone use so long as you close out the video out program (without choosing NTSC or PAL).

I used tape to cover pin 4 of my adapter, and was able to watch videos on my TV. But also - when I closed out the "video out" program at the PAL/NTSC screen (top right button, then close it in running programs) - I could then successfully connect a wired headset. I used a 2.5mm headset and held a conversation with my roommate.

I think this is great news, so you don't have to add a switch or pay $40 to an ebay scammer who has. The adapter should retain all it's functionality. Hopefully if others can confirm - there's no reason NOT to modify your stock adapter.