The only benefit of a C/R set up is a reduced minimum control speed when airborne (Vmca). An engine failure close to Vmca (since you're well below the best single engine rate of climb speed) pretty well means you're now flying a single that cannot climb (or most likely not even maintain height) therefore you're landing anyway.
The possible benefit of a left hand turning engine on a twin will be that there is no critical engine, which could be what defines a faster Vmca than with two right hand turning engines.
It is true that some twins have lackluster single engined climb, but they will have a positive rate of climb at speeds between Vmca and single engined best rate of climb speed. Or, they would not have passed certification testing.
Its an interesting study as to which way a designer chose to have the engines turning relative to the airframe - tips rotating toward or away from each other at the top. For most twins with opposing rotation engines, the props turn tips toward each other at the top. The exception to this was the P-38 Lightning, which (though I have no personal knowledge of this type) was said to have less than ideal single engined handling.