both DE and SE are good, just depends on your choice. You can play around with different ballast and bulb choices to see which one you like best, just make sure it's all within the same wattage. I have 250w PFO HQI (DE) ballasts running XM20K Single Ended bulbs. Works GREAT!!! I wanna change to Radiums though.
You can't go wrong if you get PFO DE ballasts and pendents. it'll still give you a lot of choices later down the line.