SQL Server NTFS allocation unit size

You shouldn't need to uninstall/install: your data and log files should be on separate disk arrays/SAN Luns from the binaries.

Saying that, 64k NFTS cluster is highly recommended all over the place.
SQL Server does IO in extents which is 8x8k pages = 64k, basically.

For actual numbers on performance differences, I can only find this http://tk.azurewebsites.net/2012/08/ (Azure, but still SQL Server)

Microsoft also has a nice TechNet article, Disk Partition Alignment Best Practices for SQL Server, that discusses Disk partition alignment as it relates to SQL Server 2008. In most cases, 64KB is the best choice. Best recommendation would be to make sure your partitions are aligned, test your I/O performance and if Latency and other specs are not to the level of performance that this mission critical app needs, plan for down-time and fix it right!

since you only get to do it absolutely right once before it goes to production, I'd say so but it depends on your usage patterns. If you're not already live with the system I would grab the config file which acts as a unattended install file if you reference it during your reinstall. That should make the reinstall much easier and consistent.

http://mycodelog.com/2010/09/28/sqlsilent/