According to this post I reckon your chances of swapping the drives are very good: Switching from EX4100 to PR4100 - #6 by Joerg_A as noted in the post, just make sure you maintain the drive order.
According to this post I reckon your chances of swapping the drives are very good: Switching from EX4100 to PR4100 - #6 by Joerg_A as noted in the post, just make sure you maintain the drive order.