I'm definitely a new kid on the block, so maybe I have this wrong, but I think it was said that the Delta Ceramcoat Silver is brighter than the Behr Silver; something about the Behr having some black flakes in it to make it darker.
Looking forward to the "shoot-out"!
BTW, depending on the amount of silver metallic needed in a mix, the Delta can be cheaper. It comes in 4 and 8 ounce bottles ($1.99 and $3.99 respectively at Michael's), while the Behr costs $19.99 for a 32 ounce jar at HD. Also, I've seen the Delta paints on sale at Michael's for 25% off.