Why spend over $30 more for the DS3R if you're not planning on running a RAID configuration? RAID is great for servers and such but has no advantage in gaming rigs (lets not get started on a RAID debate).
You can certainly buy what ever board you like and get one that does everything. But if you don't utilize those features then it's really extra money spent for nothing.
For $30 more, the DS3R also has four additional SATA ports (for a total of eight), one eSATA port (located in the I/O panel), and a bracket that converts two internal SATA ports into two eSATA ports. The DS3L only has four SATA ports, and two of those ports would be used right away (with the hard drive and DVD burner, which are both SATA). In this case, it's not a bad idea to spend a little bit more for some extra features.