There are two versions of the Hostage...the Hostage and the Hostage pro. Yes the brushes wear down ( I have had to replace the bottom brush, but you can also rotate them, its just an allen screw holding them on.)

The hostage pro is the only one you can shoot blazers through. The regular hostage doesnt have the diameter to do so. I bought replacement brushes and keep them in my archery tackle box, if I notice my shots are shooting low, I either rotate the sides and use a side for the bottom, or simply replace the bottom brush.

Its a great rest though. I think it beats the WB hands down because the vanes never touch a thing on the fly!