It will cost you a bit extra, but if you initially go with the IceCap ballast you'll save on a lot of heat and a lot of electricity regardless which bulb you choose. You would also be able to switch back & forth with bulbs types or even mix & match.
IMO IceCap ballasts pay for themselves completely in just a few years with the reduced power consumption and extended bulb life.
Bang
ps. I'm a really big fan of URI VHO.