Is it worth it to seal a room this size?

I have a walk in closet that has another walk in closet behind it with a door between the two. So basically its two 4x6 closets connected like traincars. I could have one be the flower and one the veg, but i wanted to do a sealed room this time instead of all the ventilation and ducting. Is that a waste of money in this space? Also would I be able to use the same air conditioner, dehumidifier, and co2 for both rooms and still have them on different light cycles, or would each have to be it's complete own sealed room meaning two of everything. in that case I would remove the door inbetween and have a long sealed flower room. Thanks for the input.

what kind of lighting are you using? Because depending how many hps lights you are running, you need to factor heat in. My closet is a little bigger and with 2 600s hps, I need an ac unit to keep it cool. But I run bare bulbs, using cool tubes co2 would work. I have used co2 and I think its a pain, but it does increase yeilds...

Growing indoors with the passive intakes and inline fans and all just seems to get so dusty and stuffy no matter what. I feel Like its impossible to keep up with the dust filters and what not. I feel a closed room can be so less inconspicuous and cleaner. I would be using 2 600 watts most likely. I don't mind keeping up with co2 and I'd rather have a controlled environment at this point.