My dreads are 7 1/2 years old. I started them by way of dreadperm, but have cut the length so frequently that all of the processed hair is long gone. I know dreadperms aren't popular here; all I can say is that the person who did mine knew what they were doing and I never had any troubles with or because of the process. It (dreadperm) only happens once, when you're initially forming dreads. Everything after is all palm rolling, maintenance, and going through the same maturation process as other dreadlocks do.
About my set: I can't have dreads longer than my waist since things become too awkward and heavy for me. I'm at the point where I'll cut again. I have my dreads maintained via crochet every 2 months. I always have a lot of new growth.