During MethodCRM downtime you are unable to access your account and therefore your data.  However, your data does remain secure.  See this knowledge base article:

Is my data secure and backed up?

Other Considerations

Although infrequent and brief, from time to time MethodCRM does go down for server maintenance, load balancing issues, etc.  If this is a concern to your business operations, you will need a strategy to handle this.  Here are options to consider:

• Access your data directly in QuickBooks.  This is provided your critical data is part of the Method/QuickBooks sync scenario.
• Use MethodCRM built-in import/export tool to export your critical data to a locally available file.
• Engage LaCrewsBSP to build an custom program or website that uses MethodCRM's API to automate the retrieval of your data.