The issue that people don't take into account is that difficulty does go up over time. Hopefully you actually hit ROI before your contract is up. Also, I wouldn't rope gpu-mining yourself and cloud-contracts up together, with the exception of those who did pay a crazy premium for their GPUs, one of the larger differences between having a rig and cloud contracts is that you can ebay your parts to recover a large portion of what you put in (even now GPUs are still going for a premium (i.e. someone who bought in at MRSP [or newegg sale+rebate] can almost get ROI alone [or more] just by selling their rigs... I can tell you this because I've been waiting for them to come down haha).