I think you forgett the natural mp regeneration of the charas, who is normaly blocked by the fire spheres of the blm.
Mean: If you are in your ice phase, should you have the naturaly mp regeneration (what will probably now be slower as before), the mp reg over time skill (for, when you are running around). And than, the fixed mp regeneration of the ice spells.
Im neutral to that.
It ruins the idea of beeing as good as possible be a pure fire mage. But, Ice feeled allways like the unwanted little brother, who you want to have away as fast as possible. Maybe, they extend the use of the ice phase somehow. It feels allways a little bad, that you dont need ice 1 ever, after you learn blizzard. Because, its the stronger ice spell with no drawbacks (except casting time).

My complaining about the blm is, that it looks like, as if whe are pressing fire4 even more now, as before. I would like to have some variation in his move set (like a firewall for a line aoe attack or so). A extended ice phase could give this maybe.
In addition did it not looked for me, as if the ice phase is truly longer now as before. It looked for me very fast over and was going back to the fire phase.

The other complain i have is more the Leylines.
Its a nice idea, to summon the lines back to you, if you are forced to go out of it.
But. i would miss the option, to jump to the leylines. Because, it could help with movement over the arena or to evade some aoe attacks (like the scorpion thing in the last dungein, where you could place the lines, and when the sand is coming, can you move instantly to the lines and are out of the danger zone).