I have TIR4 with the clip thingy for my headset. Yeah the wire is a little bit annoying, but not really so bad, especially considering that I already have a wire for my headset. My headset had a couple of small velcro strips glued to its wire in various places (I'm assuming for just this kind of thing) so I have the two wires attached to each other.. no big deal.
Even so, it would be quite easy to snip that wire and install 5v worth of batteries in place... 4 1.2v AA or AAA rechargeable batteries would probably do the trick as well... if you didn't want the wires... also I got the hat thingy also but haven't used it.. I never could wear a hat as I find them uncomfortable. Motorcycle helmet... well it's uncomfortable as well but I don't have much choice there LOL.
As for aiming... yes I have two buttons programmed on my joystick... CENTER and ON/OFF. I also don't bother with the precision setting. I also have a little bit of deadband programmed into the center of my view, so if I'm looking straight ahead, the first 1/2 inch or so of head movement doesn't 'register' to make aiming easier. I do however, often turn off TIR altogether when GVing, bombing (doesn't work with outside view anyway), and flying a plane without a reflective gunsite (like the IL2), but the immersion factor in fighters is GREATLY INCREASED.