Daceman, the guys did a really good job going over the pros and cons of SE/HQI a few days ago. If you do a search, you should find it. If not, I'm sure Deanos can find it quickly. I like XM 10,000k 250 SE on Icecap ballasts with luminarc minis and actinic supplementation. There are tons of options out there. I would consider going to other members houses and checking out what they have.
Regular sized luminarcs are better than minis, hands down. More surface area will give you more reflection. But sometimes, minis are all you can fit and are still an excellent choice (like in your case where you want actinic supplementation on a 24X24 tank). You'll get at least double what you get from spider reflectors. If you keep the base of the mini at least 12 to 14 inches over the water surface, you'll cover 3 feet.