Natural + trained = spontaneous

The above equation is one we've been working through in our Friday night classes, where instead of simply taking people through the "system" of tai chi chuan, we have placed the emphasis on the actual usage of the art. So when new people show up, the list of what we do seems incredibly short: no form, no applications, not really any fixed-step pushing hands, no weapons...
What we want to get to the bottom of is this: can we move, adapt and keep our flow under varying circumstances? We really aren't concerned with "correctness" above and beyond practicality. Did you get out of the way? Did you maintain awareness? Did you defend and keep an appropriate range? The result isn't always pretty, though sometimes it is. The "natural" side of things makes use of people's ability to avoid and evade without thought, like they brush a fly off or step around someone on the pavement. The "trained" movement  ensures they don't collapse and let an attack in, that when they arrive at a target something is there already to strike or do whatever makes sense. What we wish to avoid is the "which foot do I step with?" way of approaching the martial applications.Perhaps later, in the name of a greater technical repertoire, it may be necessary to drill applications like we used to in the old days. This is the difficulty: should we teach as we were taught? Or teach how we would have liked to have been taught? Though we are grateful to our teachers, for the moment we are going with the latter.
I figure that the above equation is the same as the "chi and jing combine to make shen", or at least corresponds very closely. I have always found that to treat "chi" as flow makes the best sense, as to me it seems like a verb and not at all like some ectoplasmic substance generated only in the sphere of certain Chinese activities.
I am not sure that the people who come to our lessons are always convinced about how "tai chi" the proceedings are: indeed, sometimes they are obviously baffled. But in every lesson they have moved and evaded and perhaps even counterattacked, again baffled that they have been able to do so: spontaneity sometimes comes swiftly.