The RB3011 has a display which is handy… The nice part about whether its “worth the upgrade”, will be your time – use the RB5009 to fiddle with V7 until your happy with it there. Then, switch the RB5009 as your main router, when ready. (And, yes you’d want to run 7.1.3, or 7.2rc4, not the 7.0.3 it comes with it)
I use VRRP a lot. Since you’d have roughly similar routers, you can could then add VRRP to your configuration to use both for redundancy if you want. V7 even sync support connection tracking for VRRP to make that a backup router work even better.
While I think I a pair of RB5009 in just 1U rackspace is kinda handy concept for a redundant setup (e.g. if you upgrade/reboot a router, internet doesn’t go down). You already have an RB3011, that seems like it make a fine “backup” one day here.