For VS2008, I believe RDL gives you better editing features than RDLC. For example, I can change the Bold on a selected amount of text in a textbox with RDL, while in RDLC it's is not possible.
RDL: abcd efgh ijklmnop
RDLC: abcd efgh ijklmnop -or- abcd efgh ijklmnop (are your only options)
This is because RDLC is using a earlier namespace/formatting from 2005, while RDL is using 2008. This however will change with VS2010