I didn't like the compromise with the bsc621.
When I would get ku peaked I had no c-band.
I bought a corotor and could not be happier.
When sadoun releases the new g box, it has polorizer servo control so you can control a high quality feedhorn with your free to air box.
You must have got a bad BSC-621, or you never had it set up right. but they will perform great for C-band even better than a co-rotor, an just as good on Ku-band as a co-rotor. but with a co-rotor you can up for more stable lnb's which is a big +, but you louse a lot the way the antenna feed come from the throat into the wave guide on a co-rotor.
now today was setting up a 10-footer on a H to H mount, an had a 621 in it, an the way this mount is its a DOG to get to track the arck. its a Channel Master, an for you're declination you have to spin the dish in its hub an every time you do it you cange the skew. so I put a co-rotor in its place today so the pan-3500 could move the ants (c & ku) with out me keep reshewing the 621, an I noticed right away on Telstar-12 that I lost 6-points on quality (had 98Q w/621 an 92Q w/co-rotor on freq 11,805) with the co-rotor, (yes good quality lnbs on co-rotor) started checking other sat that I was about the same across the board.
now I got 1 621 that I sold a freind here that I have to ship back to DMSI, I put it in the dish to day an it is deaf on ku he could not get it to work, but this is my 1st out of all that I have purchased that is bad out of about 20 or so. other than that they are good performers for the price that you pay, now if you want the most signal going go for a ortho feed they have the least loss in them, from any type of feed that I have installed.