blademedia,
As well as "Ricks Forum" it might be worth a try asking on the "Satellite Guys US" forum
SatelliteGuys.US
From what I have read, the dual band feeds can sometimes suffer from signal loss on one of the bands, however, I have no first hand experience of using such a feed so it's only what I have read.
I think that there is a rotational multi band feed available for a prime focus dish. I am not sure but it might be a company called Seavey who manufacture them? This might be an alternative option for a multi band feed for a prime focus dish. They are expensive and aimed more at the commercial market than home enthusiast, hence the high price.
Rgds