Good ref thread here: https://budgetlightforum.com/t/-/14230
Match's emitter test threads are great: https://budgetlightforum.com/t/-/16621
all this: https://budgetlightforum.com/t/-/14233
Infamous ANSI white chart: http://flashlightwiki.com/images/f/f6/Ansiwhite.jpg
The FT Convoy listings are good in that it's mostly relative, ie they say 500 (really 350), and they say 900 (really 650), so relatively they are correct. Many sources just outright lie with no basis on facts, others you can see they try by quoting specs but not accurate to how they imply. Many high end brands quote pretty good #'s though, but the budget world is the wild, wild, west.