I've bought two properties off the plan (neither was a good buy) and in each case the deposit has been lodged with the developer's solicitor to be released at settlement - no risk of losing it AIUI. The plus is that if you're an early buyer you get to choose where in the building you are (aspect/level/layout etc) but there is the risk of spec changes (the contract probably allows this) and OC fees are an unknown.
My PPOR was built by a Queensland developer who locked the OC into very expensive 25 year contracts which he sold on pre-settlement. I think this is now illegal but better to buy an established property where the outgoings are known.