Short Version: The DR 15/- works, the 200 PRR does not.
I summoned the level 25 owlbear, and went to EE Bargain of Blood. I then had the owlbear aggro the lone kobold at the very begining of the quest, and capture a video using fraps. I determined the damage from each hit by subtracting the owlbear's life post-hit from its pre-hit life. I then repeated this process using the cleric (to keep us from dying during the process) I was playing, after removing his armor, shield, and other defensive gear. So, I had no DR, and no PRR.
Note - the kobold does not have doublestrike or the like. Every attack animation against the cleric produced just a single damage number. My apologies on the small sample size (only about ~25 hits each), due to limited time. However, the sample is sufficiently strong to conclude that the PRR does not work.
Against 0 PRR, 0 DR Cleric:
Avg Damage: 95.5
Std Dev: 12.6
Against the 200 PRR, 15 DR Owlbear
Avg Damage: 73.7
Std Dev: 14.3
200 PRR should result in a reduce of 56.29% damage. That alone should have reduced the average damage to 41.74 for the owlbear. Since DR is applied first, we would expect (95.5 - 15) * (1 - .5629) = 35.2 for the average damage. We found that it is actually 73.7, a difference of 38.5, 2.7 standard deviations away. The odds of this occuring by chance are worse than 1 in 81 (assuming a normal distribution). While I'd repeat more for a formal publication, this is still good evidence that the PRR is not 200. Note that the average damage was 7 lower than expected for a 0 PRR. But that is only a half a std dev away, so this is not unexpected.