If I can add a comment from a kilt maker's standpoint who has done quite a few custom runs.

There is a minimum yardage requirement from any weaver due to how a loom is warped.
Some mills have as little as 11 meters double-width and some as much as 36 meters double-width.

And the majority of the mills today have only double width looms.

Andrew Elliot does have single width looms, so while the minimum length they can do is about the same, it is one kilt worth instead of almost 3 kilt worth of fabric.

So, If a customer truly needs just one kilt worth of fabric I would look at a mill that can weave single width fabric.

For a customer who wants more than a single kilt worth, wants a fly plaid or any accessory that needs double width fabric I would look at the quality of the fabric, the selvedge edge, and the cost - in that order.

And for double width fabric for a kilt, Andrew Elliot would not be my first choice due to one edge having "floats" where the changes in color happen. You can see these floats in the above photo.

So yes, if you are going to want single width fabric then Andrew Elliot. If you want double width then my personal preference would be - Marton Mills first, followed by Lochcarron.