Actinic are more for your viewing pleasure as opposed to the corals. Actinics make your coral's colors pop better and all around give your reef a better look (in my opinion). Your coral will love you more and grow faster under a 10k daylight HQI bulb. You can go with a 14k temp bulb if you want some blue. Some say that a 14k give the same kind of color a 50/50 would give. Not the same type light but the same overall color in the tank. If you feel like you want the additional actinics for display reasons you can always build a hood and get a retro kit. The MH fixtures that fit our cubes unfortunately will not come with actinics.
Wet Web media page on actinics:
Actinics