I've been playing on the ffa exp dm server for some time now and I've really been enjoying the experience, I think in it's current state it's better than the regular dm servers and I would fully advocate replacing current soap dm with this new ffa version. But there's still some things that could make the experience even better.
Since assists aren't counted, any class that isn't scout ends up getting their regen/kills yoinked by the other scouts in the server. I'm not too sure if you turned off assists on purpose or if tf2 doesn't allow you to get an assist against your own teammate. If you could somehow make it so that you could get assists against your own teammates this would make the experience much better. If this is not possible then maybe make it so that not everyone is put on the same team, you may not get the assist you deserved for every kill, but at least you would get it for some.
I also think you might be able to get away with adding more than 8 players on the server by adding more spawns, especially on larger 5cp maps. I would be interested to see maybe a 12 player ffa dm server with spawns that end up utilizing second points and maybe even last points.
Thanks for your servers, they've been loads of fun.