okay so heres a pic of my early flower room. i use the same 150 watt hps that you are looking at. only i use two and got mine on amazon for like 30 bux each. all the lights in here are the 2 150 hps, two clfs= to 150 watts each and one cfl thats equal to 300 watts. also there is a couple green and red t-5 flourecents in there that i took out for the pic. the oldest i let plants get under these lights is 3 weeks of flowering than i switch them to the 400watt hps. the reason why i would say go with this light is because it sounds like your trying to keep it under wrapps and this light is great for stealth because it has the built on ballast and heat isnt really a big factor. now if you went up in wattage you would have to start worrying more about heat and ventilation and remote ballasts. so with this its all in one cute lil package.
however if your trying to do more then like one of two plants all the way to havest with this light i would highly discourage it! you wont get the penitration you need and end up with a large main cola and lil baby popcorn nugs all around.
so if you do end up going with this make sure and invest later in cfls or another.
hope this can help you out.
and take a lil from what everyone says cuz this is all about personal prefferance try this try that and soon enough youll have your own lil routine down.
good luck and happy harvest!