Stratholme, so many trash mobs with so much disable. >.< It would be torture trying that on Challenge mode.
Personally I like the idea of it, but I would really like for them to focus on making the actual content challenging, rather than the time you need to beat. I've done the current Challenge Modes and whilst they were a lot of fun, I have a huge issue with easily becoming stressed when the clock is ticking, so I don't really enjoy it as much as I otherwise would have.
You can include such things as having close enrage timers, not allowing any wipes for gold and overall high skill demand for the best of the rewards, but a ticking clock on trash mobs really isn't my cup of tea, especially not in a dungeon like Stratholme or BRD. =/