Hi Vijay,
It is always recommended to be on the latest release, so I would say, better upgrade to ru6 mp1 now. Not exactly sure, when would RU7 be released.
Anyhow, you would need to be at RU6 atleast to be able to upgrade to RU7, from RU5. You would not be able to directly upgrade your SEPM, or your clients to RU7. You would have to first upgrsde to RU6.