Hi there. I had also considered BAMF in the past, but the changes done by it were a little too much for my taste. Instead I use the Balance - Character module from Wakim's Game Improvements. It is good if you want not too radical, small balancing changes to birthsigns. The changes are as follows(taken from readme):
-Increased Tower Key power open magnitude from 50-50 to 60-60
-Increased Star-curse poison from 3-3 to 3-6 magnitude
Added resist poison 25% to The Serpent
-Increased Blood of North magnitude from 2-2 to 2-4, duration from 30 to 45
Added fortify endurance +10 to Trollkin
-Added Moonshadow spell to The Shadow, chameleon 25-40 for 15 seconds, cost 5
-Added fortify luck +10 to The Thief
-Added fortify strength +10 to Wayward
-Added Charioteer Power +50 Athletics, +25 speed for 60 seconds.
-Added Wizard's Brand (existing but unassigned power) to the Mage. [Shock Damage Magnitude 50-50 area 12]