Hi Jamie,
Use fail-over, if both fail-over hosts have the same hostname, you save a CPS license. ;-) Then you can use really nice fail-over solutions from HP, IBM, or Oracle. I think even Microsoft has something to fall over ... sorry, silly pun.
The problem with active-active clusters is that you do not get the performance you would expect, so running two systems simultaneously means two licenses, which is costly and ineffective.
Don't get me wrong, multi-node clusters are supported, iirc, they are just ineffective when it comes to SAP CPS.
Regards,
HP