Jsawhitlock,
I have tried different sized bubbles, I prefer the large because they tend to last longer. Actually once I solved the sagging MDF base shelf with aluminum, the large bubbles last well over a year. At some point the air will go out and need replacing...
The sonic differences are marginal if at all. I believe I hear a difference, but this might just be my mind making up answers.
The one thing to keep in perspective (something Ken has told me in the past) is that Neuance shelves are designed to be a single shelf answer. The shelf by design "should" absorb or drain all the vibrations it receives. The need for additional isolation is by design not needed. I have argued that Bubble Wrap actually further isolates the shelf to in effect be floating in air, and thus allowing the shelf to completely be self contained. Ken (Neuance) does not follow my logic, but I have found it to sound it's best with the Bubble Wrap. I believe you will discover other products (Sorbothane) will have an affect on the sound, this in my experience is a slowing and bloating of the leading edge of notes. I personally would stay away from these type products in that it is counterproductive to the design philosophies behind Neuance. That being quick, light and rigid.
For further reading on the topic of isolation check my system post regarding isolation. Click each of the tabs to pull up complete descriptions.
Having said all that, I have found isolation products between the Neuance and components are successful and worth the cost and time.
jd