What is the benefit of Pressure Cooking (other than faster cooking)?
I do not know that there are any benefits aside from what you have already mentioned. Pressure cooking is a technique, like using the slow cooker. It is similar to a debate on broiling vs. pan-searing. They both do something similar in slightly different ways.

The only other (and totally subjective) advantage I have seen, since I primarily use the pressure cooker for stocks, is better gelatin extraction from the bones and tendons with the pressure cooker. My stocks are thicker than the old-school "simmer it all day" approach, but it may just be I'm getting better at making stock since I gave up using anything but a pressure cooker for stock years ago. Therefore my case series is a retrospective review and subject to inherent biases from the study methodology.