The Wearing of Narya

[Bombadillo]

When Gandalf faced the Balrog in Moria, he wore Narya. That left him vulnerable to the One Ring's corruptive and compomising power.

That decision leads me to my first doubt of Gandalf: What would happen if the One Ring was worn during those 10 days in which they were fighting? It doesn't seem so wizardly wise.

I've thought about Narya's healing power. He could have been "fortifying his walls" during battle. But he didn't seem to fully consider what would occur if someone slipped on the One Ring. Surely, he'd be screwed. That would have been worse than anything the Balrog alone could have done to him.
Really, he didn't even need to fight the Balrog. He sent it falling to its death, that was all good. Of course, he was pulled down with it, but he is a Maiar; he had so many alternatives.

Somebody help me out. I don't feel comfortable going against Tolkien. And please don't flame me.