Not sure how that's calculated. I assume it is accurate, but the index size is going to depend a lot on what kind of text you have and how it is separated into individual terms (or n-grams or all the other ways you can tokenize and filter to create individual terms).
Personally, I think of disk space as cheap, and am far more concerned with having options to improve speed and quality of search results.
Personally, I think of disk space as cheap, and am far more concerned with having options to improve speed and quality of search results.