Which program to backup? Single Layer or Dual Layer?

[markw]

I am interested in getting a blu-ray burner but which program is best to backup movies? Currently I use dvdshrink, dvd decypter, or dvdfab to read in a movie and then nero to burn it. At times I use AnyDVD if necessary. Which procedures are best for blu-ray?
Also, the single layer blu-ray blanks are much cheaper than dual layer. Is dual layer necessary? For DVD I almost always use single layer and only dual layer if I can't shrink onto one for some reason. Is the same type of procedure necessary for blu-ray? Can you get by with single layer most of the time?