I might be off on this but it looks like if you want the full spectrum you need both of them. The PS31 will only do LiveVu forward and RealVu Forward. The PS30 does three views, LiveVu Down, RealVu 3D Down and RealVu 3D Historical. They don't ever tell you that the PS31 will do DownVu or that the PS30 will do Forward.
What you say is true, but it is my opinion that us freshwater bass guys should make Forward the priority if purchasing both is prohibitive.
I am with you on this Todd, forward is the way i am going. A lot of what I target are smallmouth on rock piles and humps.
Yes, Panoptix Forward is going to be unreal when targeting schools of bass on offshore structure. I can't wait until later in the year when the fish move off the banks into deeper water.