I have MainConcept Suite 4.1.1 installed for use only with CS4 for importing
and editing H.264/MPEG, XDCAM, DVCPRO and AVC-Intra.
It is my understanding that the MainConcept codecs were licensed by Adobe and
integrated into the application beginning with CS5, and all of these formats are
now handled natively without the need for installing the MainConcept Suite.
I do not use the MainConcept Suite for CS5.
Unless MainConcept has changed something between v. 4.1.1 and v.5.1,
I do not believe there would be any added functionality.