Big fear for me is that eventually you could leach activity. Competing discussions on the same topic mean that neither discussion really is as active as it could be. Now at the moment it appears more likely FC will be a relatively dead zone and FT will act as off topic, but if this forum ever gains more support the splitting could start to occur. Personally Id rather have one big topic of discussion on an issue than two smaller topics with less opinions being shared but that's just me.
Sure that is a fear. Give it time and see what happens. The alternative is to force people to converse in a style they don't care for and that could just generally drive people away. This type of thing has been tried before. There was once a move to sticky "serious" discussion threads at the top of OT. It did not get much action and died a natural death. RD as well was a nice try. look at least they are being responsive. Everyone should just calm down and give it a chance.