Twin rotary rake side delivery

I’m looking at buying a twin rotary rake side delivery to replace a single rotary rake. I’m wanting to know how well the tail waggers work on hillsides. I’m also considering a two point mounted rake to help with the hills. Does the tail wagger need to be adjusted frequently across the hill or does it track with consistency? I could be totally wrong with my thinking. Is there much difference between the rakes? Salesmen around here have no experience with rotary rakes and went so far as to say they are junk. Thanks in advance for any help.

Twin rotary rake side delivery