Dong Family Style has their Fajin Form. Below are two paragraphs about the Fajin Form from Alex Dong's book called Taijiquan Explained Part II:
"The Fajin Form is fast and uses Fajin energy consistently for all the moves. It maintains a high level of intensity throughout the form. Fajin is issuing energy explosively and Shoujin is to bring back the Fajin to gather, regain, restore, and be ready. Fajin and Shoujin are forces of Yin and Yang. As soon as you use Fajin, you must use Shoujin. After Shoujin, you prepare to use Fajin again. Although the sequence is similar to the Long Form, there are many differences and the explosive energy makes it unique. The same result cannot be achieved by doing the Long Form fast. Fajin must be done properly, Qi sunk to the Dantian, the body dropped, the crown lifted, the whole body connected, spirit focused and everything synchronized to release the sharp burst of energy that is Fajin."
"The Fajin Form builds stamina, conditions the physical as well as the internal body, develops martial spirit and good Fajin energy. You must learn how to do it properly first before using a lot of Fajin. Too much to soon will create stiffness and exhaustion."
I haven't practiced the Fajin Form yet though I've seen my Teacher and others practicing it. I'm still working on the Hao Form (the third form in the sequence of four empty hand forms) and I'll probably be doing that for a couple of more years before I'm ready for the Fajin Form.
Yes, there are two fast forms, one called the Family Fast Form (in the past called Tung Ying Jie Fast Form) and the other is called Fajin Form. The Family Fast Form is a short form and consists of slow and fast movements. The Fajin Form is a long form (though since it is performed fast the length of time to do the form is relatively short).