The redundancy you want to build in your network depends on the SLA, criticality and you have to decide.
I assume you are running a Hybrid Cat6K. if you go for Dual Supervisor chassis it supports Single router mode(SRM) and Dual router mode(DRM). SRM is preferred technology over DRM as explained in the doc below.
In SRM, only one MSFC per chassis(Designated Router) is visible to the network, while in DRM both ur MSFCs on the chassis have independent view of the network.
The above configs work when you have high availability enabled on your Supervisors.
http://www.cisco.com/en/US/partner/products/hw/switches/ps708/products_white_paper09186a0080088874.shtml#wp42793
Praful
