Yes, you can simply swap the SAS 6/iR with a PERC 6/i, but if the volume is running Windows, it will not boot, so a backup/restore is necessary.  Linux should boot ok following the migration. You can also use the H200 or the H710.  The S300 can also do RAID 5 and 10, but it is a software RAID solution and performance would be worse than with the SAS 6 (and is only for Windows OS's).  The H200 has no write cache but is a 6Gbps controller - perfomance would be similar to the SAS 6.  The H700 has 512MB or 1GB of write cache, drastically improving performance, and is also a 6Gbps controller (the PERC 6 is a 3Gbps controller).
I have a PE R710 with a SAS 6/iR controller. How hard is it to swap it out with a PERC 6 or something else that will let me do RAID 5 or 10? Can I import the existing drive config in to the new controller? Which controller will work in the server?
R710 with SAS 6/iR - change RAID controller?