I always keep track of duels as a play-by-play in simulators. DevPro I can record replays and on DN I write down the plays if necessary. It makes things a bit more fun and closes things out a bit faster (I mean, some people run things like Ojamas and Exodia and Chain Burn and it just isn't fun to go against in a play-by-play in that scenario).

Custom banlist I'd argue would be nice, seeing as how some things got hit that really don't need to have been and vice versa. Stratos and Trish off the list would be cool.