i would be conservative here.
I would do 3 drain/fills, each along with the scheduled oil change.
love the inline filters. not a bad idea in case the new fluid knocks some form of debris loose. Make sure you get it installed in the proper flow direction. install it with the first atf service, change it again at the 3rd, and be done.
fluid choice. Nobody here will have a crystal ball. there is no right/wrong proven by science--- just we all have our unique experiences. I have had 1 poor maxlife experience in an otherwise fine honda AT. most people here have not had that problem. I like maxlife in an old engine-- it works. I would worry about changing ATF chemistries if the seals were getting ready to give up. we don't know the condition of yours. Over treating seals with seal conditioner can improve their performance but also weaken them, increasing the wear rate. DW-1 will be a change in chemistry-- which may or may not impact seals. but if there is not a known seal/pressure/shift problem, I'd probably avoid it.
are you certain your trans came with Z-1? at some point they used to be dex.
If it's a Z1 car, I would probably vote DW-1 (or amsoil). if you don't have a problem with leaky seals (external and internal) now, I wouldn't introduce extra chemicals. If it is shifting sluggishly or acting balky, yes I would jump on maxlife.
note there are a lot of MaxLife fans here, several honda owners have gone to it. It's got a generous additive package and people here recognize that. You are in a unique situation with having such a high mileage vehice, that may have oem fluid, that is still working properly. not everyone has all 3 considerations.
I would change it... as someone above said, you will feel a difference.
PS-- my mom has a civic with 270k+ miles on it. I do an occasional drain/fill with amsoil when she rolls into town. no leaks, no slips, no flares. I didn't touch it until she asked me to look at it around 220k. so similar situation. I didn't bother with a filter-- it made it this far without knowing if the regular services she gets for it have included the ATF.
good luck