Not at all-ASSUMING u will have adequate ventilation by way of at least having a temp controlled room, and have them "dancing" in the wind of a couple of oscillating fans.... U will find that the 400W HPS is a great choice for a small closet op, because if u get a HPS, u have the versatility of also having a MH, and can therefore buy both type lamps, and use them interchangeably... I have "open" core and coil kits, so taking my starters(ignitors)out of the ballast's circuit is a breeze, and I then run my MH's when I change my ratios of HPS/MH lights up... I would venture to say that u may not be a Journeyman electrician like myself, so the one u would most likely buy would likely be a pre-wired, enclosed set-up, BUT they will still fire up as is on a HPS, and I would definately recommend using the 400W MH for your seedling(keep plenty of space, but they love it, and will shoot up before u know it), and it will keep your internodal spacing short, so that if u decide to start pruning your vegging crop early, and often, you will create massive indoor bushes, that when u switch to the 400W HPS when u sex them, and get ready to start 12/12, u will have plenty of light for one or two big beauties... I can't help but to urge u to do this, and then, later on when u can, get a dedicated 400W MH(about $85 at a lighting supply house, for a core and coil kit, not incl lampholder and lamp), and use both 400-watterz for both periods of growth, and u can thank me for the bumper crops, then... Soundz like yer on the right road dude...