That is a really good question. I am unaware of any way to determine, prior to a sew out of a design, about the density. Perhaps someone with digitizing knowledge might answer this question.
I did have a similar problem with a design from EL, the density was so great that my needle was 'pounding' on the threads to get through. I have other of their designs without this problem, so I don't think that density is an issue all the time.

I love this basket of vegetables, but it did suffer from too dense digitizing, particularly in the asparagus on the upper left. However, It was just beautiful when I was finished and did have some 3-D effect because of the density. I did have to stabilize it very heavily.
EL has a good reputation and I would never say that I don't use them, because I do. Just be aware that your 'test out' of the design will give you this information.
Pat
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