Congrats!
Well, for the next round of changes, I think I'll add the per bot data for Melee battles and the other basic scoring options (like survival and bullet damage). There's still a bunch of basic things I need to check off my to-do list before I get too deep into the custom scoring stuff. But I do think it sounds awesome and really powerful.
Reading a custom battle listener at runtime and attaching it to the Robocode engine via control API (which I'm already using to run battles) should be pretty easy. Then you could listen to whatever events you want to and do whatever you want with the data. And if you're comfortable doing everything outside the RoboRunner infrastructure, that will be all you need.
What I see as the hard part is crafting a nice way for you to store/retrieve these score data in the data files and format custom output, which I think is necessary to make this a lot more useful. It's not rocket surgery, but I think the data file format would need an overhaul - maybe switch to something XML based. And I'm not sure about just passing a custom ScoreObject, because, for instance, right now I'm only listening for the final score from the Robocode engine, so I don't even have the data you'd want. You'd need to listen to other stuff for the per-round survival and stuff. There's a lot of options for what type of data to collect, so I don't think I want to guess and try to record all types of data you might want and just pass it along.
And sure, feel free to experiment some of this stuff, or fork the GitHub repo and go nuts. =) I made the code public domain so people can do whatever they want with it. I'm super stoked that anybody's even interested in this - I thought I'd be the only one using it while everyone else just stuck with their RoboResearch setups. =)