Evan will correct me if I'm wrong but as long as you are 80 watts or under, you should be fine. If you've got longish runs that require heavier gauge cable, it's a good idea to give yourself a little bit more breathing room.
In addition to keeping it under the 80% recommended usage (80W in this case) as Meso said, we typically advise against linking hubs/hub-to-hub connections as they can lead to voltage loss.
