Will I notice a difference between the quality of the picture between the 85mm L vs non L on a canon 20 D?

It is my understanding that the 85 non L is prone to CA.

Read this review.

that review is good...

just from personal experience the L is great for portraiture in comparison, where as the non L is what you'd want for sports n such (the L version is sloowww focus).

Anyways to directly answer your question, I don't think you'll see the difference when it comes to whether its L or not, it's the bokeh. the f/1.2 on the L is priceless.

But wouldn't 1.2 be so shallow its unusable for a portrait?

um....no

Thanks for the review link, it answered some questions for me. Now I only have to decide if bokeh is more important than weight, quick autofocus and price~