I've tried both OZ and pdaXrom and keep going back to pdaXrom on my C860, seems to meet my needs a little more. OZ was great though.
As for pdaXrom window managers, I gave wmaker a try, very slick and fast that was. Just needs a few more dockapps ported for it and it'd be greatly useable.
A lot of stuff percieved as 'missing' in pdaXrom is often available in the contrib feeds.
When my only Zaurus was a 5500 though, I stuck with Hentges' ROM. Worked great. I really suspect that if there was a version available for the C860 I'd probably be using that right now.
Kelly