Based on my experience... get the heater. I don't know about CA laws, and I sure don't live in SoCal, but if you ever drive your car to higher elevations or on cool evenings, you'll be glad to have it. If, as you say, you'll drive the car year-round and you're ordering it with a top, it only makes sense to me to have a heater. IMHO
Besides, when you drive your car to Spring Fling in June you'll be glad you ordered the heater.
