OK, very little risk. I guess nothing is zero risk.
But if your goal is to gain experience being in uncomfortable situations with LEOs it can be very close to zero risk. You just need to de-escalate when you think its at a bad turning point.
Besides, am I on the women's home journal web site or opencarry.org?
This entire site is dedicated to supporting people doing something that is risky as far as LEOs go. If you are willing to take on the risk of OCing, then refusing to chat with a cop at a sobriety ckpoint is nothing.
I guess it has a lot to do with what state you are in. Being in the Northeast, we are a lot more questioning of police than many other states. All cops have recorders in the car that they aren't supposed to be able to access. At sobriety checkpoints there are a lot of cops around. I've never had a CT trooper get belligerent, its always been local cops.
Finally, if you are going to engage in any kind of legal civil disobedience, whether its OCing or seeking out sobriety checkpoints you are an absolute fool if you don't do it with some kind of audio and/or video recorder.
If you have an iphone or android device you can download Qik and use it as a video recorder. Qik immediately stores whatever you record up in the cloud, so even if your phone is destroyed or "lost" you still have the video up on the web.
So while zero risk may not be correct, it is much less risky than open carrying and still represents a good way to get practice dealing with LEOs. If you are still concerned about risk, I'd choose to not OC while refusing to cooperate with cops at a checkpoint.
Some of us do not have the option to conceal and some refuse to pay a tax for right to conceal.