I dont know if this helps you any but I wouldn't allow a rogue to get sneak attack damage using blindsight. How do you "smell or sonar" your way into a precise, sneak attack shot?
How about a light spell to cancel out the darkness? Wouldn't that work? (whatever the 2nd lvl light spell is or whatever the opposite of darkness is).
Blindfighting feats are fairly easy for fighter monster types to get right...
If you shoot dead center of the darkness you would only get a 50% miss chance.
I would not allow the cleric to cast range touch attack spells using the blindfighting feat, or at least give them major minuses....
Toss some caltrops on the floor in front of the cleric, I would rule that they are too close to the ground to detect.
A nice rock trap that you lead the darknessed person into (ouchie for that 2 ton rock that just fell on the cleric)
Silence spells...
Dispel magic of course
Monks with expeditious retreat and spring attack (in and out of that 30' radius...)
Of course, I find that it is my mission in life to find creative ways to defeat my players creative ways of fighting. I also agree with the poster above who said you will be in for some big time disappointment if you think this is a superpowerful combo......Monsters can learn just like PC's can, have them fight and retreat and come back with some way to neutralize the players min/maxed combo........PC's who cannot adapt die quickly in my campaign

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Remember that PC's are epic characters (usually) in the story, and thus are talked about a lot (this would include their tactics, especially if the use the same one all the time).
TLG