But there's so much more than sharpness, what about the bokeh!
I think this gets played up too much as just a function of aperture, distance to subject, and subject distance to background are equally important. The rest is just pure personal taste on the quality of blur.
I disagree with you on this one. The number of aperture blades also has an effect; otherwise, all lenses would only have 5 blades like the 1.8.
Another thing to consider is the resistance to flare for the L series lenses. I borrowed a 50 1.8 and was very disappointed by the flare from light that should not produce any flare. It seriously affected the (unedited) photo I attached below.
This weekend I shot with the 35 L and had no flare issues at all. Just something else to consider when deciding on whether an L lens is worth the price.