But before A600, there was A500+ with the same level of incompatibility since both had kick 2.0. Hmm I'm not sure about if they have the same chips or not but they are probably similar.
With my 500+ I failed to run a lot of old games normally but with a degrader program like relokick most old games would work. There were only a few exclusions like final fight and some others that I can't recall but I was never upset because something didn't run on my machine.1MB chipmem felt a lot better than a 512k machine even though all I did was playing games. Also there were kick2.0 only games like ishar 3 that I loved (Can anyone confirm it does not work with 1.3? I have doubts about this)
Workbench 2.0 was much professional than 1.3 and I learned many things about computers with my A500+. I doubt I could familiarize myself with 1.3 if I hadn't seen 2.0 before.
A600 lacked the keypad and that's really annoying. I wouldn't want to use such a machine but you get used to everything in time !
Akira is an A600 guy I think he has lots to add.