I have a Thiers-Issard Alum block, I use it for every shave, just love the stuff, does wonders for my skin and the feeling is fantastic. After a year, it's just starting to get noticeably thinner, which means in about another year or two, this one should be done.
When this one goes, I have an Osma Alum Block ready to go. The two friends of mine I got into shaving with a DE, the alum block is their favorite thing, and the one thing I notice they all bring up if shaving with, "an old fashioned cartridge" type razor comes up.