I have been reading several threads on the sorcerer. As written, it has a few extras, but I won't be able to get anyone in my group to play one. In general, though, I really LIKE the idea of the sorcerer having a bloodline.
I like the balance mentioned above in giving them increased caster level, and I am one of those that doesn't want the sorcerer to become a gish character.
Perhaps the Sorcerer could be given extra spells known based on their bloodline? Perhaps even go so far as one extra spell per two character levels. Giving them one per two would offset their spellcasting slower spell progression. A choice of possible spells wouldn't be too outrageous IMHO.