Glenn when I got mine I was looking at the same options as you.
The main reason I got Pro Spec is because of centax clutch (which I think costs the same as the diff in price from normal to pro). But if you didn't really want the clutch the normal MTX2 could be good too!
I think Pro Spec parts such as Sway bars, Front one-way are not definately better just different (if that makes sense). You can take the sway bars off but if you want to use normal diff you will have to buy this.
Other options included on Pro: wide front bumper, belt tensioner with ball bearings, aluminium wheel hexes. Someone on this board said that the Pro has better quality bearings also!
I think some places in the USA have the Pro with the MT12, pipe, tires and body but not sure about in Australia. My Pro-Spec was just chassis kit for $800 Aus.
Hope this helps you!
