I have seen many Singapore citizens who renounced Singapore citizenship and now regret - correction, deeply regret - their decision. The fact that they have withdrawn their CPF monies is of little consolation.
Whatever misgivings you may have about Singapore, the fact remains that Singapore is still your home. In a foreign country (Australia, Canada, USA, New Zealand, wherever) you are and always will be a lesser human being, and you will always be short-changed and exploited when it comes to work and earning a living. You WILL face racially-motivated hostility and prejudice.
Want to rough it out for a few years overseas? Gain overseas work experience? Gain overseas life experience? Take up a second citizenship like what many other Singaporeans have done? (by right and by Singapore law dual-citizenship is disallowed, but by left, well just "don't ask, don't tell"). By all means do so. Has anyone heard of anyone else who has been publicly prosecuted for holding dual citizenship? No, I didn't think so. As long as you're not a trouble-maker and not publicly bad-mouthing anyone, no one will give you any trouble. Until you actually receive official notice from the Singapore Immigration Authority, why not just continue to tread that fine line? You have nothing to lose. Or just continue holding on to your Australian PR and renew it every few years when the time comes. You can call both Singapore and Australia home.
DO NOT give up your Singapore citizenship. Don't burn all your bridges. Retain your Singapore citizenship because eventualities will arise, and you will be grateful that you still have a way out, you still have a way back home.
Do not learn things the hard way. Take this piece of advice: do not give up Singapore citizenship. If anything untoward happens to you and you find yourself a victim in your new adopted home, viciously harrassed and harangued on all sides, you will have no way out and you will be well and truly alone. You will well and truly be at the mercy of your enemies. You may be temperate and peaceable, not the type to make an enemy out of anyone, wanting nothing more than a happy and peaceable life, but there will be legions out there who will only be too glad to make an enemy out of you for no other reason than because of your ethnicity and the fact that you are a foreigner.
In a foreign land, you are nothing more than a resource to be exploited. The attitude taken towards you will be clinically calculated, detached, methodical and unconscionable exploitation.