Personally I think these additions would make them a +1 LA. Born with magic may need wording to prevent it from working with Shadow Craft Mage, I'm not totally sure.

Born with Magic: Gnomes gain a number of Spell-Like Abilities based on their hit die. Each has a caster level equal to hit die and DC based on CHA.
1: Silent Image 3/day, Ghost Sound 3/day, Prestidigitation At-Will
3: Ghost Sound At-Will
5: Minor Image 3/day
7: Silent Image At-Will
9: Major Image 3/day
11: Minor Image At-Will
13: Hallucinatory Terrain 3/Day
15: Major Image At-Will
17: Persistent Image 3/day
19: Programmed Image 3/day

Subtle Magicians: A gnome who knows the feat Silent Spell or Still Spell automatically learns the other as a bonus feat. Additionally if he is a spontaneous caster he may apply these metamagic without increasing the casting time.