Given how little of the Generations line has skipped Aussie retail in recent years I wouldn't be preordering any Hasbro product and if a wave does get missed I'd then goto TLTC and buy it after the fact.

That said though I buy the Takara Tomy versions normally (but not all the time) because they are more cartoon accurate in most cases and you have little choice but to preorder them if you don't want to buy them at a huge markup on ebay.

Plus don't forget Amazon is potentially days if not hours away from opening it's Aussie site to more than just books and Amazon is very likely to get every wave.