I posed the question to them and they replied that, because its a download, there won't be any issues like there could be should it be a region-coded DVD. However I've heard rumours around the traps of Steam restricting your activation based on your location ie. like region-locking which means we have to buy the overpriced Aussie version instead of the cheaper US version if we want to activate it.
As for Steam...mate, I buy stuff off there all the time and I actually like Steam - I've lost a hard drive and all I had to do to recover my games (that I purchased off Steam) was to redownload!!