A couple of years ago during Taiji Camp, Laoshi explained that his version of the 48 is more inline with the Chen Village Laojia, or Old Frame, and that this is the way GM Feng first taught the form in the early 80s when he formulated it and when Yang began training with him.
The idea behind the Essential 48, compared to the Refined 48, is an emphasis on Gongfu, or basic skill development, especially the Eight Energies. This makes a lot of sense if you look at the way Taiji has been taught historically. In Chen Taiji, the first form (48 for us) is the Gongfu form. Its purpose is to develop and nurture basic skills. This is fundamental to any art, especially Taijiquan. We get the opportunity to develop the extra circles, and the attending Neigong, as we learn the Er Lu, or Pao Chui form, the Sabre form, and all the various Hunyuan Gong exercises. And we should be better prepared to learn the advanced forms with a solid Gongfu foundation built through extensive development of the Essential 48 Form. To that end, the 48 form should be our primary, most-practiced, form.
A year or so ago I was listening to a podcast with a guy who is a strength coach for professional basketball players. He told a story of how when he was first getting started he had the opportunity to meet Kobe Bryant. Kobe invited him to one of his workouts. This guy arrived early to find Kobe already in the gym with his personal coach doing basic movement drills. Apparently these drills were real basic, the kind of thing one learns in middle school basketball. Afterwards, he asks Kobe why, being the best basketball player in the universe, he was still doing basic skill drills. Kobe's reply was that doing basic skill drills daily was the reason he was the best basketball player in the universe.
To illustrate what I am saying consider the following. Below is a video of Wang Feming doing the Refined 48. This is exceptional. However, notice the difference compared to how we practice.
Now consider the below video of Chen Zhenglei doing the Old Frame, or Laojia Form. Note, that while the arrangement is different (it is a different form), the energy is more inline with the way we (students of Yang, Laoshi) practice the Chen 48.