If you think a pre-print is a better source than an academic letter (published in a reputable scientific journal, which implies at least editorial review), then lets agree to disagree.
If you cannot reliably judge the legitimacy of a pre-print in an area, then you aren't qualified to judge the legitimacy of any scientific comment in that area.
> If you cannot reliably judge the legitimacy of a pre-print in an area, then you aren't qualified to judge the legitimacy of any scientific comment in that area.
I agree, but now we are moving into the content and not just judging the book by its cover.