Grading is a funny thing, especially non-CGC versus CGC.
I'm just now getting back up to speed as a grader after buying comics years ago, storing them, forgetting about them, and now selling them or prepping them for sales.
In the sales of raw books I've done on eBay, people are happy with my grades in their feedback. Which to me suggests that I'm either in line with other collectors grading, or grade more harshly than other collectors.
But I've sent stuff to CGC that I thought would be a 4.5 and it came back 3.5, or an 8.0 and it came back 6.0, or a 2.0 and it came back a 1.0. So I personally have given up trying to have an expectation of what CGC will give as a grade. Really just hoping that in the end it all balances out.