Well there is a broad spread consisting of steelhead/salmon, striper, tropical, warmwater and trout anglers here on the Forum - unlike some communities that are very trout-centric so it's bound to produce a less concentrated point of view on well-established things like the X rating.
However there's always some value in learning things like this, one never knows when it will come in handy.
I like the trick of subtracting from 11, thanks. Just subtract the X number from the meaningful digits in .011 to get the diam, right? E-Z.
For instance, take river levels. Some guys have a mental image of gauge height in feet while others only in cubic feet per second. Frankly, I can tell which rocks stick out of one river based on gauge height alone but need the CFS to have a clue about another river's fishability because of the basis of how I came to know them each.
A system is right when it works for you, and to be open to many systems is to be a smarter angler IMHO.
So an 8x is only .003? wow talk about spider web! Couldn't even floss my teeth with that after shore lunch.