I am sure about Residency Obligation Appeal. I don't have any idea about refusal appeal. For that actually the letter (if u r given right to appeal) or the website (if it is a standard procedure) is to be seen thoroughly.
Also I think the refusal is from local CHC & not from CIO, Sydney. However if u think it's right u can reapply after updating the score achievement & apply after few months / years instead of wasting time, money & energy for appeal. Also u need to check success ratio in the types of your appeals. Also u won't be able to reply till the appeal is finalized once u go for appeal/
Actually I have done so. I could go for appeal regarding 'Residency Obligation of PR'. But instead I gave my Appeal rights, revoked my PR status & now applying again! Anyway it your own choice!