Hokum or not, scientific studies or not...I wear them on most of my long runs and afterwards for the rest of they day. It seems to help me. My wife as well.
She has CEP I have Zensah - Both pretty much the same. The bummer is...they ain't cheap. Cho Pat seem to be the cheapest..the 2xu ones seem to 'look' the coolest ;) (http://gearwestbike.com/articles/2xu-compression-calf-sleeve-pg386.htm). I was pretty bummed when after I spent 100$ on socks and sleeves, and the next day went to the Nurse store with my wife to get scrubs for her work, there was a wall full of compression socks for 6.99!
I have Zensah calf sleeves and 2XU shorts. Only anecdotal observations, but I am under the impression that they help with fatigue on long runs and aid in recovery. Don't know if it is only a placebo effect, but I am fine with that. They also add some additional warmth in the cold weather.
Aside from the performance/recovery factor, one definite benefit is that the shorts eliminate any chaffing issues I used to have on 20+ mile runs. That alone makes them worth it to me.
The downside is that I feel like an ass wearing knee high socks with shorts.
"This is Watchung, not Siberia. Nothing bad will happen"...except bear attacks apparently!
Len i have the knee high 2xu compression race sock. They have worked great for me on long runs and i noticed that my legs have more life. The only draw back is that there a pain to get off and espically put on. However unlike Chris i do like the style of knee high socks and shorts. I actually might get a pair as well.