Second one I agree with, the first one I don't.
The Okay response varies.. Dependimg when it appears in the argument, and why.
I use it mainly in person as the person I was arguing with disregarded my opinion and continued to hammer on with theres despite me telling them I understood what they meant but it wasn't going change my opinion, so I said it to end of settle the argument. usually if your talking to someone thats being weirdly aggressive and discounting your personal opinion, it's a waste of time to continue, so an okay and leaving it there is fine, it tends to piss off those kinds of people that are looking for an argument and total submission/gratification rather than a open discussion.
Although if the okay comes right after an opinion with no 2nd opinion, then that person doesn't care to discuss or want to acknowledge you, rude.. But fine. Although sometimes people's opinions start of so delusion that only the word 'Okay' comes to mind.