I don't know about the technical side (it will take more ram, more cpu, or not, bla bla) but I see 2 other points there.
Yeah, I'm wondering if there is any technical downside. If there is, I doubt it would be major since it's only text and not even text that needs to be triggered in like a split second or anything.
First grouping or separating will depend on your engine (like having an ini file in each folder containing the images of the group or something like that or rather a single data.ini in the root folder).
It is somehow a matter of taste.
The sprites inside the layout are blank, meaning that you'd have two groups of fighters and based on which groups you select, the loop index--based on a global variable--will bring in the correct groups and populate the blank sprite positions at runtime (this I already know how to do). Also, based on the group, Construct will recognize the attributes in the .ini file and change each sprite's private variable attributes to match those in the .ini file. This will only need to take place once per game in the opening fighter group selection screen, so it won't affect actual gameplay.
What I'm not sure about it, is whether keeping all of these things in one file is a good or bad idea, or if separating each fighter group into its own file is a better idea.
The other point I see is that through .ini files, ppl will be able to modify the values of the fighters and groups in the notepad. Once again, depending on your engine it might be an issue.
If you want to prevent people from accessing those datas, you may create a simple editor, place all your datas in a hashtable and export it. Than in your game, load the hashtable and there are your datas.
You could still edit those through your editor, but simple notepad edit would be discarded.
I want them to be able to edit the file. My goal is to make an engine that can be fully edited by the end user even if they don't have Construct or any desire to learn it, so as far as I can tell using .ini's seems to be the path of least resistance to that goal.
SIDENOTE: The post preview function is not working. Please forgive me if this is already a known issue. Thanks