I haven't read Fatal Error, Reprisal, or The Dark at the End, yet, but I just ordered them.

Though I enjoyed them all, (today) my top 4 would be:
The Tomb
The Haunted Air
By The Sword (maybe because I read Black Wind before this one)
Harbingers (or Bloodline)

I agree that the Santa fix was one of the best short fixes. In fact, when I explain RJ to others, that is the vehicle that I use.