According to Psychology book:
There are three levels of moral development: At the preconventional level, moral thinking is guided by self-interest and the consequences of actions (punishment, reward, or an exchange of favors). In the Conventional stage, reasoning is based on a desire to please others or to follow socially accepted rules and values. The advanced moral reasoning of the postconventional level follows higher, self-accepted moral principles, not thos supplied by outside authorities. ... People advance through the stages at different rates and many fail to reach the postconventional stage. In fact, many do not even reach the conventional level. For example, a survey in England revealed that 11 percent of men and 3 percent of women would commit murder for $1 million if they could be sure of getting away with the crime.
As for the question in the op, I am not even going to think about it because I think it would be a sin to do so. But if the question were something like: If God hadn't set laws for us regarding how to act and wouldn't judge us or punish us for our actions then would you behave less morally? My answer would be, I hope I wouldn't act less morally.
I believe it's possible for a person to be so perfect that they wouldn't do anything wrong even if Allah gave them the permission to do whatever they like as is shown in the Holy Quraan, Surah 18 (Al-Kahf) Verses 83-88:
83. And they ask you about Dhul-Qarnain. Say: "I shall recite to you something of his story."
84. Verily, We established him in the earth, and We gave him the means of everything.
85. So he followed a way.
86. Until, when he reached the setting place of the sun, he found it setting in a spring of black muddy (or hot) water. And he found near it a people. We (Allah) said (by inspiration): "O Dhul-Qarnain! Either you punish them, or treat them with kindness."
87. He said: "As for him (a disbeliever in the Oneness of Allah) who does wrong, we shall punish him; and then he will be brought back unto his Lord; Who will punish him with a terrible torment (Hell).
88. "But as for him who believes (in Allah's Oneness) and works righteousness, he shall have the best reward, (Paradise), and we (Dhul-Qarnain) shall speak unto him mild words (as instructions)."
I believe everyone should strive to attain such perfection. It may be the nafsul mutmainnah as stated in the Quraan Surah 89 (Al-Fajr) verses 27 - 30:
27. (It will be said to the pious): "O (you) the one in (complete) rest and satisfaction!
28. "Come back to your Lord, Well-pleased (yourself) and well-pleasing unto Him!
29. "Enter you, then, among My honoured slaves,
30. "And enter you My Paradise!"