The biggest thing that can get to me with the Monk class is the ramp up with Greased Lightning. It kind of feels like an intentional troll mechanic that laughs at your DPS plummeting anytime the boss runs away or god forbid you are targeted with an onslaught of AoEs. So far the Form Shift ideas I see here would be great on solving that. I am also thinking they could do something similar to what they did for Dragoons to improve on the ramp up effect. The damage increasing portion could be removed from GL and migrated into potency buffs to all of the attacks. That way if you do lose the buff, only the haste bonus is noticed.

The Fist Stances could also use some rework so we aren't always stuck to the highest DPS one. It may be possible all 3 should have the 5% damage increase so we just use the stance with the secondary effect we want. Fist of Wind could have an enmity reducing modifier added with the speed boost. Fist of Earth would already be good with the 5% damage boost added. Fist of Fire would be the tricky one and the best I can think of for the moment is either a healing increase self buff or a minor leech heal effect of maybe 30% of damage dealt from Coeurl moves.

The Riddle abilities are also odd since they have unneeded costs or restrictions on them. For starters, they should work with any of the 3 Fist Stances. Riddle of Fire could guarantee all your weaponskills grant an extra Chakra and the haste cost can be removed in exchange for the damage increase effect to be nerfed down to around 10%ish. Riddle of Earth's effect also shouldn't need you to take damage to trigger it and just give you the buffs it offers.