I've read about many people who have been using HOT-ROX and Spike in an alternating fashion. HOT-ROX one day, Spike the next, etc depending on your goals and which you like to use prior to specific activities (Spike before lifting and so on).
I haven't tried this for any extended periods, but I never had any problems alternating like that - worked just dandy.
I wouldn't opt for combining them both in the same day. If you need to drop a lot of fat, stick with HOT-ROX. If you only want to lose a moderate amount of fat try the alternating days protocol.
Personally, when I'm using HOT-ROX, I go with Power Drive for a mental boost.
Hope this helps a bit.