Yes, I am flying UA mostly.

At IAD, they have a separate security line for international transfers to get back into the terminal (is that what "midfield transfer" means?), they don't throw you back with the general population like they do at Newark and ORD. So even though there's no TSA-Pre line, I've found the lines to generally be shorter than the general lines at other airports. IAD was my preferred United hub for re-entering before I got Global Entry. I am Flying through IAD in a few weeks, (on a 2-hour layover) so maybe my opinion will change.