Another SPD-SL user here. My experience is similar to nscrbug's except to add that I also wear mine for triathlons and so far, the cleat is holding up remarkably well.

I will say that these are by far my favorite pedal/cleat combination. I have zero issues clipping in at all. The pedals are one-sided, but I think they are weighted (unlike my first pair, 6 years ago) so that they naturally just fall into the right position for clipping in. I have the Ultegra version on my road bike and the 105 version on my tri bike. I use the same shoes with both.

My commuter has the 2-bold SPD's because I rarely ever ride that bike for more than 25-30 miles and I figured I'd want the two-sided pedal and the shoes with tread when commuting. The combination is OK but honestly, the connection is not as smooth as the SPD-SL's for me. YMMV.