I'm convinced that larger domes are most comfortable and healthier to use as they spread the pressures more evenly across a wider area.
You are right.
We want to be suctioning as much of the surface area as possible. That being said, it's very dependent on torso breadth.
Right too.
If the breast fills the dome completely, the effect of suction is not rather intense any more.
The internal diameter of domes is very important.
I think that more than 14 cm am already too big, even for the new XL.
The internal diameter of the medium dome with the length of the new XL would be needed.
I note that the more the internal diameter is big and the more the skin under armpits is inhaled.
Breast under arms is not wanted...
I think that this form of dome (see picture down), with a withdrawal on the base would be the best system.
The internal diameter could be 12/13 cm.
The base of the breast could stretch in the dome.
The dome would hold better on the thorax.
But it should not be easy to fabricate with plastic injection.
I do not see how it would be possible to withdraw the mould of injection of the inside of the dome...