I have a couple of Aldi bits and pieces (gloves, middle layers etc) and have been really surprised by their quality. I have mates who swear by their jackets / pants - if they've got your size then I wouldn't hesitate to buy them.
That being said, the US will have a far bigger range and more brands / styles (Aldi tends to have one or two styles, and it's really obvious if you ever head to perisher when you see about 20% of people with the same jacket).
Where in the US are you headed? I bought a bunch of sale gear in Portland from US Outdoor (REI is also excellent) and it was dirt cheap - about US $250 got me north face pants, patagonia jacket and some burton gloves (but I hated the gloves and probably wouldn't buy burton gear again). I bought cheap (~$8) Aldi mittens, cause I didn't know if I liked mittens, and they've been bulletproof. Cheap and featureless, but bulletproof - water resistant and warm enough to keep my fingers working in Hokkaido this year, which stunned me. I'm now looking for a nice pair of mittens as I'm a convert. But I digress.
Personally I would go the USA, which should be cheaper in Feb than just about anywhere in .au during even sales. Incidentally, if anyone knows a good place to get quality mittens, I'm all ears (I'm back in the US in a couple of months).
Also ski boots - any thoughts as to good boot fitters either in Sydney or in the US? I've had my boots for about 8 years now and bits are starting to fall off them, the inners are worn out, and I'm thinking they may have done their duty...