Lawnaire 28 or Rock Solid PL600

I'm looking at getting a walk behind aerator and would like to see some pros and cons of both machines from people who have them.

I can purchase a used but in good shape Ryan Lawnaire 28 for the asking price of $900. I probably can go a little lower. If I purchase a used one, what should I look for on one of these machines. I demoed it and it was very nice. How does it do on med to small hills? Will it pull itself up hills?

I am also looking at a Rock Solid PL600. It looks good. I have never seen or tried one other than the video online.

I'm would be using it on small lots and hills.

Thanks

David