[NiHaoMike]

Bitcoin doesn't use very much bandwidth at all. Some altcoins are bandwidth intensive, but I haven't seen one that would significantly slow down anything that could be called decent Internet nowadays.

The main downside of the energy efficient coins (using hard drive space or cheap smartphones) is that the hardware costs tend to be more significant. Mining more or less self regulates to be barely profitable, so if energy is not a significant cost, hardware is. The real winners are those who have jumped in before the difficulty level spiked, something that I did with a number of altcoins.