I've only seen TUF3 and TUF4, but I agree that the 'coaches' concept of TUF3 was more entertaining than the 'trainers' concept of TUF4.
Mixing newbies with veterans sounds interesting. You're bound to get some good conflict out of that:
Vet: You better listen to me, boy.
Noob: Shut up you has-been.
Vet: What have you done? I've fought Shamrock, Ortiz, and Liddell! Show some respect!
Noob: And you lost to each of them! Shut up, old man! Respect is earned in the ring.
... and so on
By the way it part of the TUF4 contract that they couldn't wear shirts in the house? Or did the UFC just not have enough shirts to go around? Every time I saw them in the house I was thinking "Put some clothes on, dammit!"
1. a finishing stroke; anything that effectually ends or settles
2. discharge or release from life.
3. a period of retirement or inactivity.