Out of Ten Games with me and a friend playing Kayle/Katarina bot lane...

We won nine. Against a variety of lane comps, most of them meta (things like Graves/Blitzcrank or Jinx/Thresh) and non-meta (Sona/Rengar being the standout). In addition to preying on the enemy ADC, we have just as savage of a late game as teams with marksmen on them. I don't go AP Kayle, for that matter. We even won a 4v5 in the enemy's favor. The S4 gold items allowed this to be possible.

Teambuilder is the best addition to LoL ever... and I intend to keep playing this combo because of how risky it is, but how good it feels to pull it off.

http://matchhistory.na.leagueoflegends.com/en/#match-history/NA/33840125 - Check it, filter Kayle games. The last ten were all Kayle/Katarina.