After rereading the article abt how concentration checks work :
http://paizo.com/pathfinderRPG/prd/coreRulebook/magic.html#concentration
..
Its my opinion that caster classes are already facing deep hindrances after getting hit.
DC by 10+damage+spell-lvl
vs.
D20 + CL + attribute
thats quite an obstacle to bypass. Even more assuming that the damage output increases on higher levels faster than the casters lvl or attribute..
Not added in any backstabbing attempts, or flanking, or a barbarians rage
My 2 Cents ;)
