Based on my study under Asai Tetsuhiko, I believe that the highest level of karate skill and impact power is found in junansei (softness). Prior to accessing private trainings with Asai Sensei, my prime focus was foremostly to make maximum power. Nowadays, my number one aim is to always be in a state of relaxation, to achieve the 'softness', Asai Sensei was always referring to. This challenge may seem simple, but in reality it is physically ongoing and very demanding. The softer you can make your waza, a deeper level of junansei is revealed, and the deeper you go, the more 'impact power' you can generate (or better put, transfer).
My training in karate-do, particularly the extensive private lessons with Asai Sensei, have snow balled for me, enabling me to have a greater appreciation of the internal arts, such as Tai Chi Chuan, Aikido etc. It has also helped me to see, that like karate, many of the instructors, teaching these arts, are merely demonstrating the external forms. This is the trend when too much focus is on martial 'sports', the practitioner is an amatuer (or poorly trained), or simply, they are a show-off.
How I approach junansei in my own training
In conclusion I'd like to say that regardless of what I am working on, that junansei is my physical priority. Others, who wish to follow Asai Sensei's karate way, must not Shotokanize it, but rather aim to make their Shotokan soft. If you can make a 'committed physical effort' to erradicating muscular tension in your karate, you have found the essence of Asai Karate.