Well when I started reading about cones I was a bit undecided myself, there seems to be benefits as well as problems with using them but it really depends on the individual.
I use whatever conditioner I like I don't worry so much about the cones because I don't have issues with them building up on my hair. I use a sulfate free shampoo that lathers up adequately and removes them from my hair.
I don't really know if they create a barrier for moisture but I haven't seen any evidence of this with my hair.
I do try to use my shampoo on the days I want to do a deep treatment but I can go weeks using conditioners with cones and co-washing my hair without getting build up.