Ok, my opinion about the A-600:
Nice little computer
Already 1MB chipram inside
Kick 2.0 makes WB 2.0 possible which is a lot nicer than WB 1.3
Keypad missing ( not a big problem since only few people use it )
Some software doesn't run with Kick 2.0
Some very old software doesn't like more than 512k. So no chance to get them running on the A-600 since you cannot switch down to 512k.
Those damn SMD chips !!!
That's the biggest disadvantage of the A-600 imho. If one chip gets fried you can trash the board ( or spend hours desoldering chips ). On the A-500 you can just exchange every chip easily since they are all socketed
That's a big advantage in troubleshooting, too !