You can switch between Apple devices (iPhone, iPad, etc.) or between any other device platform we support (Blackberry, Android, etc.) but you cannot switch between iOS and any other platform.
Due to the way Apple's certification and royalty policy works, it costs us approximately 20% more to produce an iPhone/iPod-compatible WakeMate than one for any other device. In order to keep our prices low, we decided to avoid increasing our costs by 20% across the board at the cost of a non-universally compatible WakeMate.
We are considering the idea of a reduced-price "exchange service" for those who'd like to switch to/from an Apple device, but nothing has been finalized yet.