I'm sure you are tired of hearing from me about my opinion, but I would still go with Pepperdine.
Personally I do not think it is that hard to be in the top 20% at Pepperdine, but that being said I am in the top 10% so my opinion may be a little biased. Basically I feel that if you are willing to put in the work then you can be in the top 20%.
See my post on the Pepperdine Student Taking any questions thread to see what I think abut the students and professors at Pepperdine. Basically I cannot say enough how helpful and friendly everyone is. I love all of my professors and I have a great time hanging out with my classmates both inside and outside of class.
As far as how much people study, the best example I can give is how much I personally study. I usually spend about 3 to 4 hours a night preparing for class (that includes reading and briefing). Then I would say I spend about another 4 hours a week outlining. If I have a midterm I would say that my amount of studying goes up for that week and then it goes up to bout 6 to 7 hours a day during finals. Overall it is managable and you can still have a life outside of law school.
Of course I would pick Pepperdine.