Title says it all; I've heard in the past about someone getting banned without botting, but was using the OSBOT client to play manually. Anyone else have any similar experiences? 

this is possible but a very small chance 

I cant say I have heard of people getting banned for just using the client to manually play, I remember logging on by accident once because I wasn't paying attention and having a heart attack and my account is still here xD

You can be banned for playing any client unless it's the official one. I've had one of my accounts banned for using Runelite+ without any of the OP plug-ins for a macroing minor. Never ever botted the account either. Something must flag jagex's bot detection system into thinking some clients or some plug-ins are macros. Do it at your own risk. I don't see the point in playing on the client if you're not using it for botting purposes.

I think you CAN get banned, but the chance is just a bit slim. If you want to play on it, be prepared in the end a ban might come. 

I have experienced this using Stealth but that was back in March, I would babysit, my bot, but like thing is i would not even bot for 5mins, pretty much i would be doing more than baby sitting like i am actually playing. I would take control, and all I used were paid scripts(possible flagged ip) but i remember I would reset my IP. Then I went to mirror mode and it has never happened since.

Thanks everyone for the replies, so it looks like it is possible but very little chance.