Roland teaches at my yard and whilst i dont have lessons with him myself (my horse is only rising 3 and my comp horse has just had a foal) he does seem good, and i know people do like him.
I have heard good things about Hannah and I would personally choose her over Roland as i feel her teaching style would suit me more than his - however its all down to individual preference and who works well for one person might not work well for others.
Really sorry but I dont have any experience with Roland..
However:
I really rate Hannah.. She is incredibly kind and gives extremely sound advice. It's also fantastic that she is so flexible so she was able to fit in around my very hectic school commitments. I would definitely recommend her - she also used to do clinics at BYRDS on a regular basis if that is any help?