Hi!
Strictly comparing the 2 models, the A1000 is much harder to upgrade. The A500 had many more model specific hardware upgrades than the A1000 too. The expansion slot while supposedly technically compatible, are on opposite ends of the computer and upside down(?) on the A1000. Meaning, realistically you can't use most expansions from the A500 on the A1000.
IMO what is an important question is, what do you want to do with it? Both models have their strong points, but the A1000s is mainly nostalgia value and looks.
