I understand (I think) the caveats overview in the link provided from the plugin, i.e. http://wpusersplugin.com/1822/comment-totals-by-authors/.
I have a fairly simple site, with three users who have provided comments (and replies). The total number is 97 in the Comments area (not sure how many of these are 'replies'. Akismet reporting shows 39, 38, and 20 "approved" items for Users 1 - 3, so that aligns.
As well, WP Stats page (under the dashboard tab) shows:
So that ties with total and Akismet.
I set-up a report reporting both Comments count and Replies count and got the following (comments / replies):
User 1 29 / 3
User 2 38 / 2
User 3 20 / 3
First item is a question, does the comments count (essentially) include replies?
Presuming the answer to this is 'Yes", then users 2 and 3 have counts that align. However User 1 is showing 10 fewer than he should.
Any thoughts on what might be causeing this reconciliation problem or how I might debug this?