Yeah, this concept video definitely gives off a different feeling than Episode 01. I'm glad you linked me to it.
Just want to start off by saying that, except for the Audio Portal, I'm not very active in the Newgrounds community. I know you've released a ton of animations in the past, and some of those videos seem to be part of a series. Unfortunately, I'm unfamiliar with your other work, so maybe this next statement doesn't really apply since I'm only basing it off on Gunmetal's 1st episode and this concept animation, but I definitely think your work comes out stronger when you're not tied down by having to establish a character's personality or setting up the series' story.
Because this concept starts off in the middle of an episode (That's how I see it, anyways), technically, the characters have already been established. So as a viewer, I'm not concerned about seeing any character development, and I'm not seeking any background history (Unlike how I felt during Episode 1). I simply accepted that these three were friends, fighters, and on some sort of mission. It's not as easy to just accept things on a 1st episode, however, so I can see where the struggle came in in regards to writing the script for that episode.
The dialogue worked well in here, too. Straight to the point and had no filler. I also liked how your tried to show one's personality through subtle details such as their walk. Su-Chan, for example, had this particular march as she entered the fighting room, and Ryu had a relaxed, 'hands-behind-head' manner as he approached the area. It's a minor detail, but every subtle difference really adds a lot, and subtlety is important. Nothing about the animation told me "Look at Ryu! Look at how he walks! He's cool, isn't he? Oh, and check out Su-Chan with her little march. Boy, she sure is bubbly!" And I like that you didn't tell me that. The way it is now, it's more genuine, and I've come to interpret the personality of the character, and I think having the audience come to that conclusion is better than having the story force the idea onto a viewer.
The battle was also better. Perhaps the 'lack on contrast during fight scenes' comment I made in my previous review only applied to that particular scene in Episode 1, and maybe you've never done it before, so I guess you really don't have to pay that comment any mind. I was able to see things much clearer in here. The only improvement I can suggest is that that animation can be a bit smoother (Not really an issue though since this was released this past September, and I believe the months of experience you've gained since then will show in your next piece).
And while this was mostly action, the few bits of humor in here were better received than what I found in episode 1. This is kind of in the same light as the whole 'genuine' bit I gave two paragraphs above. I appreciated the fact that when something humorous occurred, nothing was done to indicate that it was funny. Kinda hard to explain, but think of most sitcoms. Whenever something funny happens, a laugh track is played, telling the viewer, "This was funny and you should laugh." I like to give genuine laughs, and not laugh when the show tells me, too. I kinda felt like this happened in Episode 1, so some laughs were a bit forced. But in here, it was perfectly fine. When Su-Chan was missing in battle and there her outline flashed for a second, it immediately went to the next scene. I really liked that. You didn't drag it out, so the humor wasn't forced. Same goes for when Su asked Ryu if they've arrived, yet it was Su's job to keep track of their distance. This also got a chuckle out of me. It wasn't forced, it wasn't dragged. 'Laugh if you want. If not, that's fine, whatever, we're moving on.' I felt that during this piece, and it worked well.
I honestly can't decide whether I enjoyed the Concept video or Episode 1 more. I do think this Concept was well-put together, but I also like the experience of being immersed into a new world and learning about new characters, which I get from Episode 1. Perhaps one day you can combine the best from both worlds either into future episodes or a new series altogether.
At first, the whole episode skipping idea put me off a bit (and honestly, it still kinda does). I would've liked to see the show progress episode by episode... buuut I also understand why you're doing it and how difficult it would be to create an entire series without any mishaps, loss of resources, or a simple lack of motivation happening along the way. Hopefully this process works out for you and you get to practice your animation skills with different scenarios, settings, and characters. I'll be interested in seeing what comes out of all this.
P.S.: I apologize for the wall of text (again). I could've just said "This is cool" and called it a day, but I do like to be as in-depth as I can be, in hopes that I can provide some sort of help to the author. Honestly, I only write so much because I really appreciate the work you put in to this, and I think you have amazing potential. I'd kill to be able to do something like this.