ORIGINAL: Matt / PA
www.fuelthehunt.com
To answer your question, yeah they will wear out first, they have to........I just don't know how long that takes. They are an insert though so each bristle set can be replaced.
One neat feature of having threee separate brushes is that you can rotate them around when the bottom brushshows signs of wear, this way you get 3 times the use out of them.
Oh, and as Matt eluded to, the Hostage Pro is a great rest.