The team I have at the moment consists of

Team A
LF: Tidus (Auroch)
RF: Larbeight (Beast)
MF: Irga Ronso (Ronso)
LD: Naida (Al Bhed)
RD: Pah Guado (Guado)
GL: Raudy (Goer)

I'm currently at Lv 50-60 so there is plenty of time to exchange and develop players.

I was thinking of trying this team

Team B
LF: Datto (Auroch)
RF: Nedus (Al Bhed)
MF: Nav Guado (Guado)
LD: Irga Ronso (Ronso)
RD: Kulukan (Beast)
GL: Raudy (Goer)

My only concern is the forwards are weak defensively and the defenders a little slow.

Would it be better to have average speed forwards and quick defenders (Team A) or vice versa (Team B)?