I have two Judas trees and I grew one in my previous house - they are beautiful trees and pretty slow growing the flower in Winter on bare stems I have a white one with the lovely fresh green leaves and one call Forest Pansy which has mave flowers with beautiful ruby red leaves. Both do not like a lot of heat - no root problems that I know of and I think they are supposed to be drought tolerant but I found mine struggled last year but again it was its second year.
Leyla

The bad news is that the warm humid Illawarra coast is not the ideal climate for Cercis. They will survive OK and may even grow quite old, but in my experience are unlikely to produce their fine display of bright pink blossom on almost bare twigs that you see in the cooler and drier tableland towns. But depending on microclimate, you could still be lucky.

I live in the Illawarra and my neighbour's mature Cercis siliquastrum is covered in mauve-pink flowers as I write. It has a beautiful umbrella shaped canopy with attractive round leaves. it's a goer! What I want to know is if "Forest Pansy "-the purple leafed relative will grow in the Illawarra with reasonable colour. I'm at the point of jumping in anyway and taking a punt.