This background is sloppy tho
Right so let me write up my general opinion on what we have so far. The director, Katsuichi Nakayama, is a complete wildcard. He directed some no name show, Good Witch of the West, back in 2006. I recently went back and watched a few of the episodes there and wasn't impressed with his storyboarding. He also recently directed Planetarian however he was a co-director on that and that series was really Naokatsu Tsuda's baby. He's also worked as an assistant director on a number of projects such as the Bodacious Space Pirates movie and the Evangelion Rebuild movies. So he does have experience working on mecha but there isn't any real solitary work recently to judge his qualities overall as a director on. He has gotten better since 2006 but I wouldn't characterize his storyboarding as exceptional. Honestly I don't even know how they picked him in the first place. It might have been that Horiuchi recommended him since Horiuchi worked with him on the Bodacious Space Pirates movie. The hope would be that he uses his Khara/Gainax contacts to get some of them working on this but who the hell knows. As for Gatoh, Gatoh is Gatoh. Supposedly he's written the scripts for the entire show already so hopefully that means they can start production sooner and ramp that quality up.
Osamu Horiuchi has been the Chief Animation Director and Character Designer for all seasons of Full Metal Panic. As seen, his quality can vary from Gonzo level to KyoAni level. Obviously a lot of this depends on the production scheduling. Still though, at least the character designs should be faithful to prior incarnations. It was almost a given that he would be coming back due to how much work he put into previous adaptations and he's not doing shit nowadays anyway. What's interesting on the character animation side is Aya Yamamoto who did a small amount of character animation direction for the second season of My Teen Romantic Comedy SNAFU. She hasn't done much so again it's hard to get a grasp on her capabilities. SNAFU TOO was well animated but that has less to do with her but rather the production as a whole. Takeshi Yoshioka has some experience and was one of the Chief Animation Directors for Valkyrie Mermaid that while being perverted as all hell, was fairly well animated. He was an Animation Director on the gorgeously animated first episode of Towanoquon and apparently was one of the three main animators for the series. I'm not sure how extensive his role will be in FMP IV as he's listed as the small arms designer and animation director, so I guess he's responsible for the hand gunfights? He's more of a mechanical animator as seen by his prior BONES work on Captain Earth and Eureka Seven AO. As for the mechanical designers, Kanetake Ebikawa and Toshiaki Ihara, they are both designers from the original light novels so I'm not sure if they really have to do anything. Maybe there are some tweaks that are involved or they have to come up with settei (formal animation outlines) for the mechs.
So my understanding is that the mecha animation is going to be a combination of CGI and 2D and it reflects that with the animators they picked, as they have experience with that. Masanori Nishii is a great pick as he was the Chief Mechanical Director for Yamato 2199 and he's done a bunch of work for Ebikawa's designs for Gundam 00. Below him is Takuya Matsumura who did a shitload of work on Lagrange, Exodus, and Broken Blade. My guess is that the studio/director is going to try and emulate the mix of 2D/CGI in the previously mentioned works. Here's an example of the 2D in Fafner Exodus:
I don't know if they're generally going to go for 2D and use CGI in the shots where it's just too hard to do in 2D or if it's going to be like Fafner Exodus where most of the mechs are in CGI except when they're not moving. Studio Orange wasn't mentioned however they do have a dedicated CGI director with Shōsuke Uechi who was the CG Technical Chief in Yamato 2199 so I don't know if they're going to outsource it to Sunrise D.I.D. again. The main question goes back to whether the mechs are going to be primarily 2D or CGI as that is going to have a heavy influence on the style of the show and the people they picked could go in either direction. Nakayama, the series director, has had experience working with both 2D and 3D mechs such as in Diebuster, Gurren Lagann, and the Rebuild Evangelion movies.
Honestly I can't tell whether this is 2D or CGI.
Then there's three big remaining question marks, the composer and the director of photography. If they get Takashi Aoki then this will definitely look on par with the KyoAni versions, possibly better. His work on Yamato 2199 and Fafner Exodus has been beyond reproach but it's possible he might be busy with Yamato 2202. He however did retweet the FMP news so it's possible he's working on it after all. The other person that could be the director of photography is Atsushi Iwasaki who has worked with Nakayama multiple times in the past on Satelight shows. Obviously Aoki would be preferable but who knows. As for the composer they played Toshihiko Sahashi's music but didn't announce him as composer so I'm scratching my head at that. Not to mention there wasn't any mention of the art director. A notable pick currently working at Xebec would be Hiroshi Kato who is the art director for Neon Genesis Evangelion, including the Rebuild movies. Kato is mindbogglingly enough working on Keijo, which frankly doesn't visually look all that good. He still worked (is working) on NGE though. Nakayama has also worked with the legendary art director Hiromasa Ogura on the Bodacious Space Pirates movie but who knows if that'll happen.
In conclusion, it's not a bad staff list but there's a lot of ????? that haven't been filled in. The producer repeatedly mentioned Yamato 2199 in regards to the staff so I'm guessing they're trying to pick up as many people from that production as possible but Yamato 2202 is also coming out next year so I'm not sure how strained Xebec is going to be trying to put out two mechanical animation heavy series in one year.