Yeah, don't get the impression you need TrackIR. Most people don't use it.
Spot on. I use head-tracking, as do several of my squaddies, but you absolutely do not need it to play AH. It's just a nice way to get more immersion in the game. Aces High's view system is pretty darned good as it is, with huge customization capability, so your hat switch will still get plenty of use.
You're also not locked into using it if you hook one up. You can turn head-tracking off and on with one key press. In addition, AH's hat views work well in tandem with head-tracking, so that you can run TrackIR, and if you're just too busy to move your head or whatever, just hit your rear view on the hat switch and AH will momentarily override the TIR system. Let go the hat switch, and you're back to head-tracking. Best of both worlds.
Also, TrackIR is the standard for this stuff, but if you're on a budget, you can download a free system called FreeTrack (just google it). It's not as slick as TIR, but it's free. You have to do-it-yourself a bit, but it'll save you a lot of money. I use Freetrack in combination with a TrackIR LED headclip ($35 if bought separately). Works fine for me, but YMMV.
You'll find that AH, by design or happy accident, is highly configurable, customizable, scalable, and offers lots of side-activities to keep you busy, even when you're not playing the game itself. You can make historical a/c skins, maps and terrains, develop offline missions, cobble together video AARs and machinimas, create custom soundpacks, organize or participate in scenarios and mini-scenarios, join a racing league... and... and... (what'd I forget?). Lots of folks build simpits for this addiction, and AH works great with 3-monitor+head-tracking systems. I cobbled mine together for pennies on the dollar. In short, if you get bored with arena play, you'll find a lot to do on the side.
Welcome to Aces High.
...