As far as the breaking strength, the improved clinch knot (ICK) looks to have a better knot strength than the Davy, based on the literature. However, those knot tests tend to deal with higher pound fluorocarbon lines. From experience, the Davy knot is probably in the same ballpark, but where the Davy knot displays an advantage centers around the ability to tie small flies on the tippet, without the “bulky” wrap of an ICK.
regards,
pat