Your biggest issue is that it will give you to much edge in PvP.
Having the primary dmg abilities on casted rather than insta timers forces ranged to stand still. This is because some CC doesnt affect you like it does classes that do NOT worry about casted vs insta. For example your Melee toons require 4-10 range to do most dmg. Ranged require cast times for most abilities (high dmg ones)
The reason is the difference in root/snare vs interupts. Because root snares affect those that require to be close, and interupts affect those with cast times. If a merc's dmg was insta based with 30 range, they would be immune to both interupts and root/snares. This is why the changes are unwise. Name one class that can currently maximize damage from 11+range with insta cast abilities?
all CC affects range exactly the same as it affects melee.......
please explain to me how instant cast stops me from being rooted/snared? they are not even related remotely.......
sniper is massively effective at 30+m, because they are a very well designed class. they are uninterruptable and unchargeable when in cover, and have a very good full CC immunity ability. are they able to be killed by melee still? absolutely, it just requires some good play.
Merc needs a way to maintain its damage output while under pressure. Right now, if you assume equal skill and gear, Merc will lose to any melee class, except maybe operatives.