I tried the Orso on with flimsy stockings, knit tights, and skinny cords. It worked with each. Truth be told, its stretch panels were never really "activated" -- not even over my cords -- but the material is not so soft that the boot slouched. (Riding boots should be sleek & streamlined in my book, or maybe rugged & rustic, but not slouchy. That's a whole other style.)
There is an interesting "arching" detail on the heel that might put some off, but I found it pretty and flattering. Not really a selling point, but not a negative either. What is a selling point is the high-quality look, feel and (yes, I'll go there) smell of these boots.
Calf slimness: *****/5
In black or brown.
Find it at: (as of Feb. 2016) it looks like ebay is the only option left
***fall 2014 update***