the tibloc teeth can do some damage. Personally, I replace my load-bearing rope every 2 to 3 years, and within that time, I've not had a problem with tiblocs significantly damaging the rope. The damage can be limited by how you use them. From what I've been told in SWR courses, ANY rope that will carry a load should be replaced at that interval, even if you've never loaded it. This is due to UV or water damage. Sand can get in the rope and abraid the rope internally. How many z-rigs will you set in two or three years? How much damage can you do with a tibloc in that amount of time? I mean, it's not like your using it as an ascender every weekend, ya know?
When I retire a rope from active load duty, it usually becomes a tarp line or raft bow line or something like that. Throw rope if it's the right size, or junk rope for steep hike-ins where lowering boats by rope.
Tiblocs are smaller and faster than prussiks, and don't create a possible entrapment issue. We recently had an IK pin in a 6-foot ledge, and it was an interesting situation. The paddler was partially under the curtain, being held in his boat by both thighstraps and the force of the water. We needed the rope system and we needed it fast. Tiblocs are instant -- prusiks have the be dressed and tensioned properly, and loosened and redressed when moving them on the rope. I'd guess using tiblocs got us to the paddler at least a minute faster than prusiks.
That said, I usually carry 6-8 prusiks on multiday trips because they are so versatile when rigging tarps.
But for speed, nothing beats the tibloc. And you don't have to worry about abrasion/weakening issues since of the prusiks themselves, or whether you have the right diameter prusik cord for that 1/4, 3/8 or 11mm rope that someone is carrying.
just my $0.02. I hear I might be a gearhead ...