I think I just came up with a decent fix for Careful Attack and Sure Strike to at least upgrade them to Cs or Bs, without being unbalanced.
+2 to hit, -2 to damage. Essentially it is an inverse power attack.
Lets look at it now. You have 18 dex using a longbow. Normally you have +6 hit 1d10+4 damage. Careful attack gives you +8 hit for 1d10 dmg. -4 damage for +2 to hit? The higher your dex, the worse it sucks. Lame.
Now the fixed version. Careful attack gives you +8 hit for 1d10+2 dmg. Compare to twin striking giving +6 to hit twice, each doing 1d10 dmg.
Assume an enemy has AC 17. A regular attack does an average of 4.5 damage. The Careful attack does an average of 3 damage. The Fixed Careful attack does an average of 5 damage. Twin Strike does an average of 5 damage as well.
Now lets take a higher level example. The character is level 20, has a +6 dex bonus, and a +3 weapon. he has +21 to hit and does 1d10+9 dmg with a regular attack. With Careful attack (RAW) he has +23 to hit and does 1d10+3 damage. Fixed Careful Attack he has +23 to hit and does 1d10+7 dmg. Twin Strike has two +21 attacks each doing 1d10+3 damage.
Assume the enemy has an AC of 32. His regular attack does an average of 7 damage. Careful attack (RAW) does 4.8 damage. Fixed Careful Attack does 7.2 damage. Twin Strike does 8 damage.
This fix keeps them relatively balanced, makes the at will still better than a regular attack, and continues to be useful even at level 20.