2x150W MHs would be fine and really shouldn't have heat issues. You don't really start getting "hot" until about 250ish. However, 6-T-5s would be fine as well. LEDs can work, but IMO it's much more important to have a good understanding of some more advanced topics than with other lights. If you don't understand the terms "PAR", "PUR", "optics", "CRI", "photo-saturation", "photo-inhibition" etc... then LEDs may be more of a gamble. If you can find someone with a similar set-up that's really producing good results, then you can probably get away with just copying what they are doing. Unfortunately LEDs are still new enough, and offer such a wide range of configurations, that it isn't always (maybe even often) the case, so, you tend to need to know a bit more to avoid getting burned IMHO.