Eh, I think player taste matters more than designer intent when determining if a rules system is for you. A narrative system might have the perfect ratio of rules-to-rulings based on designer intent, but if you don't like narrative systems, you won't enjoy it. Lots of people love mustard, I hate it, even if it's the best mustard ever made.
The tricky part here is that since SR games have been crunchy in the past (Lots of rules), the player base already has an expectation of the rule system to err more towards "rules" over "rulings." So, you might be able to evaluate the ratio against other editions or your expectations. I think when people talk about a game being "functional," they mean "does this meet player base expectations?" or "does this meet my expectations?"
It's also tricky when the rules-to-rulings varies by section (Magic vs Matrix vs Combat, etc). You can also evaluate the consistency of the ratio.
And the hardest part of all of this is that whether something is a rule or a ruling is subjective. I count an implied rule as a ruling because not everyone will come to the same conclusion, and I only count rules that are actually in a book. Others might not. For example, I counted "Essence starts at 6" as a ruling, not a rule, until errata put it into the book. There were several places that had thresholds of "5 - Essence," so someone who is completely new to SR might assume that Essence starts at 5 instead. However, Essence has been 6 in every other edition of SR, so it was also reasonable to say that it started at 6. Some people might've put "essence starts at 6" as a rule even prior to errata, since it was "obvious" (to past players of SR) that essence starts at 6.