Accuracy: Keep the current perfect system because it would absolutely aggravating and stupid for everyone to try getting 2 less perfects than the other person for a decent rank. Like qqwref said, it creates a huge disconnection between a regular player and a topmost player that
usually does MA. It would be interesting to display for statistic/info purposes, but shouldn't actually affect scoring itself.
Difficulty: Single difficulties per song is already fine. Multiple charts can mean a rushed file. However, the judging should be less strict towards the option of multiple charts for a song especially if they are all good.
Arrows: Keep to 4key. Solo is just making this game more like KBO and stepmania, and I really wouldn't want FFR to lose its uniqueness just to conform to "more expressive styles of stepping". Solo may be fun to
a very SMALL part of the community. If you consider how many stepmania players do solo right now, I don't think many people would even bother to improve on solo. At most, 6 key should be optional (like token level ranks not counting toward your public ranks).
Multiplayer: More than 2 would be beast. Make it like SMO maybe, so it shows scores but doesn't show everyone playing at once so there isn't ridiculous lag especially if someone is spamming the chat in the room.
Mines and holds: No for both - Mines just add visual complexity to a file, making it harder to read, and creating fake difficulty. Of course you might say "but they'll make the file more interesting" - from stepmania experience, files mainly just mines that are annoying and ruin the chart. The boo system is already like having mines everywhere (if you get a boo, you don't get an AAA, just like if you hit a mine in stepmania you don't get an AAA). Holds are just annoying too and most people nowadays overuse them with miniholds and holdstream patterns, ending up just making the song harder to read/hit for no real reason. KBO, TS, and SM have holds, and making FFR have holds wouldn't make it FFR anymore.
You don't need mines or holds to express a file. You also don't need six keys to express a file. If you have to abuse holds to try "making a file expressive", then it's not memorable. I think you guys should take a look at this post:
http://www.flashflashrevolution.com/...4&postcount=14
If mines or holds were added in this game, I would most likely quit. I'm dead serious. Don't ruin FFR like that.