On the question of whether challenge caches cause me to change the ol' geocaching rut I find myself in from time to time ... yes, they do, but that's a positive side of challenges, they cause me to go consider finding more multis, or higher rating caches, or travel bugs. It's a question of how you look at it -- if you want to cache the same way every time you go out, then just overlook the challenge caches that would cause you to do otherwise.
On the topic of power trails of challenge caches ... how are those any better than a surge of pill bottles under light poles in every parking lot up and down the main drag through town? Some cachers love LPCs, other cachers loathe them, but LPCs aren't under as much scrutiny as challenges.
It all boils down to this game can be enjoyed by many people in many different ways. It's up to the individual to choose how he/she are going to play the game on a given day, week, year, etc. Some cachers log a cache online if they see the container, and that's good enough for them ... others log a find if they visit the coordinates ... others (I fall in this category) won't log a find until my name is on the log book.
Ultimately, cache owners of challenge caches need to be as dedicated and persevering as the owners of traditionals ... unfortunately, there's a growing number of those as well who aren't checking on a string of DNFs, full log books, etc.
