They sell avgas here as racegas, but you can also buy proper race gas (hard to find) at $6-7 a litre (so US$3-3.50 or so a LITRE, not a gallon). If you talk to pretty much any Kiwi and they mention race gas, they will be meaning avgas.
It is not unusual and goes in all sorts of bikes for MX, enduros, trails, harescrambles, whatever (except I doubt it goes in trials bikes somehow lol). As for smelling good, I much prefer pump gas with motul 800 to avgas with it, but don't notice it anymore anyway ;)
I run a 50/50 mix of 96 & avgas, which was recommended to me by the previous owner (Chris Birch), as the KDX didn't like straight avgas or straight 96. I'm not sure if you're in Auckland or where. My jetting's not 100%, but is okay - it just suffers spooge. I've got a PC pipe, FMF muffler, pretty much no airbox, radvalve, boyeseen reeds and think that's about it. Had to run premium the other week as left it too late to get avgas. It was slightly harder to start, but it's a good standby.
BTW, your pipe is probably a rev pipe as they're the most common FMF pipes over here. I'm one of the few I know of that's got a torque pipe - it's a lot fatter to look at & kept being asked what the hell pipe I had on my bike when I was running with it. If it looks very similar to the PC, it's definitely a rev.
Hope that helps some.