Here's what I love about Flex Raiding:
Seeing boss mechanics and learning how to deal with them for normal modes.
Guides are great, love guides, dungeon journal is great, video guides are the best (quick shout out to pallie, I use many of his guides to get my grounding in things). BUT, there's nothing quite like seeing the fight yourself. Yeah, things don't hit as hard, you'll have to adjust some in normal mode, but it allows you to see mechanics, if you get hit hard by something you can go "oh... that's probably gonna hit harder in normal, I need to note that" and it allows you to nail down a general strategy, especially from a tanking perspective.
I can't express how much I love flex and wish it would have come out instead of LFR.
"If the world is something you accept rather than interpret, then you're susceptible to the influence of charismatic idiots." -Neil deGrasee Tyson
Twitter @Aggathon || @Tankspot || Twitch.Tv/Aggathon