Just to let you know, doesnt matter if you have 100 Cast, 5000 or 9459495495, the limit is 95% and it doesnt change.
It does change quite alot in a pvp vs an archer example.. you can use only 95% cast right but the debuffs will decrease of the whole cast .... so 660% cast - 50% cast = 610% but 110% - 50% = 60% cast ....
little difference?!