12 hours a day... Hm. As Bradd already pointed out, it could be, that you won't get 1,5 times as much done if you simply work 12 hours instead of 8, because of lapse of concentration. I can only speak from my experience (ymmv), but for me, doing this once in a while is ok: If something needs to be ready till tomorrow morning, ok working until midnight might get it done. But if I worked 12 hours every day for a longer time, I really doubt that I would get 1,5 times as much work done.
So, personally, I would really love the Sleep Regulator, but I doubt that I could work much longer in one job with it. Perhaps doing two very different jobs would work better...