Brass life will be BETTER with a lee loader than with using a set of standard dies, as it neck sizes only. Works the brass less. Especially if you're using a rimmed cartridge.
My only complaints about the lee loaders I have is the .38 special version requires you to either lube the cases or pound like a maniac to set (or set off!) the primers. The rifle version I have is nice and smooth. I did learn a trick to seating the primers with the pistol version, however. If you tap the case about 1/8" out of the die before placing it over the primer, you don't have to deal with the resistance of the case against the die when seating the primer, and it goes in very easily. The drawback is that you have to be very careful that the primer is aligned properly with the primer pocket, since the guide formed by the die and primer seater is no longer flush. With my new method, I've never set off a primer, and it reduces fatigue and noise, not to mention eliminates exploding primers during the seating operation. Of course, not an issue with rifle loaders, but It makes all the difference with the pistol versions of the lee loader.