It's important how you store your fluorocarbon. I've never had a problem with most brands. I always thought Climax was too stiff, but didn't really have problems with it otherwise. I usually use Rio Fluoro and have had great success with it.
I tie six turn blood knots and wet them well before cinching. Then I'lleave and 1/8 tag. No problems with knot slippage when working within 2 tippet sizes. When using heavier line, I will leave longer tags and flash melt them with a lighter. This creates a bulb on the tag that will not slip through the knot.