Hi Petawhaz, I have worked with precision lnb's C & Ku, an their is no comparision with them to a low khz norsat lnb. The reason why is that some times when I will set up a dish I will have a Spectrum Aniz hook up also an when you are on a satellite an you're looking at all the transponders you can see just how clean a lnb is or how un-clean or dirty a lnb is, an the precisions I would put them into the same class as a eagle aspen. now the way that times have changed in satellite you're temp factor has been a major selling point for retailers an buyers, an with the low temps some times it is a trade off with the local osclator in the lnb, so they can have the gain but will get a lot more noise with that signal. an in most cases with weak signals a clean signal will lock an play over a stronger signal with a lot of noise.
now some of the less costly lnb that I have used that work good with DSR receiver is the California Amplifer, Gardener, an Chapperal, now the norm for most of these types of lnb is about 750 to 1000khz stability, but if you got a 500khz or a 250khz norsat it will perform better by far. but remrmber a good grade lnb is no fix for a smaller dish or under size dish or a poor tune dish, or a real long run of cable, but a good grade lnb will help a lot on the HBO's on Galaxy-14 to lock quicker, that just a standard high khz lnb. now here I use a lot of different types of lnbs just about what I have on hand at that time.
now for a Ku lnb what I got on 2 dishes, an realy impressed with them is Galant, have them in 500khz an 100khz & .5 &.6 flavors, an they both work a little better than the 4508 norsats that are on a ortho feed. Galant is a company that supplys 2 way internet to company's that (like car dealerships ect.) need a high speed internet service, an some times you can pick these up on flee-bay for a fraction of their cost because people have not heard of them. an if you get 1 of these remove the notch frequency plate in the wave guide of the lnb, they are made by Japan Radio for Galant people, an they are a real clean lnb.
Hope all helps Petawhaz on the lnb's, an good luck to you.