SRM 5.0 compatibility with Webdynpro

Deciding whether to implement SRM 5.0, or be a ramp-up customer and install SRM 7.0. Some experts told us that our current WebDynPro environment is incompatible with SRM 5.0. Can anyone shed light on this? Our landscape is: 2004s/7.0, BI 7.0, ECC 6.0.

Thanks in advance.