Sixth Water is different than Lower Mesa. Mesa is more pushy, and the drops are drops not steep slides. The gauge says it is 2700cfs so it will be super pushy, and not a good first run if you only have runs like Sixth Water, and Bridal Vail under your belt. Plus unless you are going to be in the Ashton area or close by it is kind of a long drive just for Mesa. I would start at Sheep Falls #1, and paddle to Upper Mesa. Then portage Upper Mesa, and if you can get down there( I never found the path.) Run Middle Mesa to Lower Mesa, and scout it. Then if you feel good run Lower Mesa. I am not one to tell others what to, and what not to paddle, but just think it out. If you drive up there, and you don't feel it walk away grab a burger at Big Juds, eat some Huckle Berry ice cream at the fishing shop next door, and drive back. No video or run is worth getting hurt.
Question: Is Lower Mesa Falls strait forward?
Answer: Yes, but the wrong mistake could hurt you or worse.
Question: I have seen people on youtube running it, doesn't look that big.... So is it bigger in person?
Answer: When looking online it looks like a 1in drop followed by a 2in drop. It looks bigger in person.
My blog link below has a video from sheep falls, and lower mesa falls in the september archive.