I played both classes at a very top level and I can say at 2.5 at nearly every encounter the SMN had the upper hand over the BLM. The SMN was always better if there are more than 2 targets, and that's nearly in every fight. The DPS of a SMN at Ramuh, Ifrit, Levi or King Mog due to the many targets was just incredible. Yes, there were some mana issues but not really a big deal. I saw some SMN spamming Ruin II even if they stay still and complaining about mana issues then...I have the BLM at 60 and I loves the new mechanics behind the new skills but it's just not FF14 friendly. The punishment for moving is now to huge as it was already. After many runs at fraktal I'm getting used to it at the boss fights. But it can't be that you need perfect experience of the fight to play your class proper. At the moment I can't see any reason to play a BLM over the SMN at endgame content where movement is vital. I'm maining BLM since 2.0 and its just not enjoyable anymore.