that LNB is really designed for a Sky dish so it won't work quite as efficiently as a standard LNB
Do you mean that the feedhorn is elliptical, to match the elliptical form of a Sky dish?
The movie on this website shows what looks like a circular feedhorn (at 01:02): GeoSync | Professional Signal Reception
https://www.alltrade.co.uk/public/product/gk4lb-quad-lnb-user-guide-v2-pdf.pdf just says: feedhorn "optimized for offset dish".
So I don't really see a special Sky-dish property of this LNB, only that the LNB bracket fits the arm of a sky dish.
Am I missing something?
Greetz,
A33