I have the seen the Hotchkiss bar. It would be interesting to know how the hollow bar fares against the solid version. I see the Eibach bar you have. It looks more like the Pierce/TB torsion bar types. I haven't added poly bushings to the front or adjustable endlinks either. Have you?
I have also wondered about that. In my 2011 Fiesta the Eibach was a huge improvement and the only easily available choice (in early 2011).The addition of OZ wheels and shaved Dunlop Direzza ss tires really sharpened the steering response. The Ford M-FR3-FA Fiesta handling pack became the weak link immediately after I got those items bolted on. The Ford kit was ok as a street driven package, but the damping rate was not compatible with all the changes. The best way to describe how it felt on the street is "twitchy". I didn't change the front ASB. I just tightened it up to be more balanced with the now tighter rear behavior. So, it got a pair of Energy Suspension poly frame bushings and a pair of Powergrid adjustable end links.
The frosting on the cake was the availability of Koni Sport dampers. I contacted Koni North America several months prior to receiving the Fiesta, they didn't have the coming Fiesta in their U.S. product development schedule. I offered to send them some parts for evaluation and measurement ahead of sending them my Fiesta for fitment.
The Koni Sports are truly superb. They really tie all the other changes together.
There are a few other things I plan to try in the future, but that will be done on a different Fiesta yet to be aquired.