I can't help but feel that you on concentrating to much on end game, and not enough on front game. This is great for the players who will be starting out at the begining, and hard core LARPers who join later, but what about the new LARPers who want to give your game a try in the future? Also, you assume that all players will pre-make characters, and have awesome character histories. I suggest that you assume other wise.
I have two different spell cost progressions to suggest.
1st 2,2,2,2
2nd 3,3,3,3
3rd 4,4,4,4
4th 5,5,5,5
5th 6,6,6,6
6th 7,7,7,7
7th 8,8,8,8
This will put a full column at 140 (112), but give new characters one more spell at start.
1st 1,1,1,1
2nd 2,2,2,2
3rd 3,3,3,3
4th 5,5,5,5
5th 6,6,6,6
6th 7,7,7,7
7th 10,10,10,10
This will put a full column at 136 (108), but give new characters four more spells, or three spells and a weapon.
All I really want to see is casters as viable as melee at front game. A starting melee going for one weapon fighting could start with one prof and one strength (not including any racial).
Although with as much as you want a column to cost, and the short duration of buffs, I am not sure how viable casters are long term either. But I guess that is what alpha is for.