Thanx everybody)

m-dynamics,
As I can see all the shapes that can be made with sweep or network can be made with loft except 2 things:
tubes are easier to built with sweep, and "caps" surface from 3 - 5 curves with network.
But with creating all other shapes Loft is the best, it's much more easy and "topology" is much more clear.
I'll say more, I started to use loft instead of sweep to make tubes for variable fillet cuts which I made in tutorial. In many cases it's more easier to control may be except when rail curves are complicated.