IMO these two will compete for a position for most of the year.
Both play basically the exact same role.
They can play back, capable of a role on the taller types or the medium types. Whilst they don't exactly dominate, they CAN do the job.
Likewise, they can contribute to the side playing as a HFF. Power is the quicker of the two, and perhaps more creative, but Monty's experience enables him to position himself in the right spots - see The Elimination Final.
For mine I think Power's best position is on a HFF. Monty, I'm not so sure. Certainly at his peak Monty was a better player down back, but last year perhaps it's the forward line?
What's your thoughts on it all?