So traditional Calvinistic OSAS: retains "the necessity for a genuine faith to be saved", but "you can never be sure of your salvation because there is always tomorrow's potential failure of faith to show that what you thought was saving faith today proved not to be that at all".
Non-OSAS is the doctrine of security: "As long as you believe in Christ ... you are saved."
For a believer living right this moment, both forms of security look exactly the same. I believe in Christ, I trust in Christ, therefore, I belong to Christ and I am saved by Christ. It is for this reason that I do not get too worked up if someone believes in the Non-OSAS view presented above. However, whatever your BELIEF, the risk for the believer is exactly the same. You could walk away from Jesus tomorrow (many who profess Christ eventually do). If Traditional Calvinistic OSAS is TRUE, then your walking away proves that "you were never really of us" [1 John 2:19]. If Non-OSAS is TRUE, then your walking away proves that you no longer believe and are no longer saved. Whichever view is TRUE, the believer living today faces the exact same danger of walking away tomorrow. In either case, what you thought today was a faith that would carry you all the way to Heaven, could be proven tomorrow to have been not up to the task.
The Bible says that tomorrow is not promised to us, so we must live in today. For the Believer who holds to the Non-OSAS security, you have the assurance that you believe at this moment and your conviction that you are resolved to continue to hold on to the Christ who first loved you. I find it hard to 'hate' someone for believing that. For the believer who holds onto the traditional Calvinist OSAS security, we have the assurance that we believe at this moment and are convinced that this is because our 'faith', our ability to believe is a gift from God - only He gave it and only He can take it back. I am forever surprised by how many people hate our trust and reverence for the Soverignty of God.
For both the OSAS (traditional Calvinist) and Non-OSAS believer, the thought of letting go of Christ and just seeing what would happen is anathema. Anyone who really doesn't care whether they follow Jesus or not is not any type of believer (OSAS or Non-OSAS) [John 10:26-27]. The Non-OSAS believer thinks that if he, hypothetically, were to let go of Jesus, that he would discover that the believer had been holding on to his belief, thus safeguarding his salvation. Perhaps he is right. Perhaps he would. I can only speak for me and my beliefs and my experiences. I do not think that I laid hold of the Christ, but that He laid hold of me. I keenly remember the day I was prepared to walk away from Christ, and He intervened to forbid it. I tried and failed to walk away. Because of my personal experiences, I must believe that if a believer were to, hypothetically, let go of Jesus, then that believer would discover that it was, in fact, Jesus who was tightly holding on to you. [John 6:44]