More and more businesses are upgrading their existing SharePoint 2010 search solutions to FAST Search for SharePoint. Doing so will most likely require scheduled downtime when you make the actual switch.
This can be avoided by cleverly upgrading your existing Search Service Application to a FAST Query SSA.
Want to learn more? Head over to my article at NothingButSharePoint.com for the details - http://pzl.no/qKacHz.