It goes both ways honestly in terms of arguing which test is "trending higher".
On the old MCAT, 57th percentile in the Bio section was good enough to get you a 10. 38th percentile or something I think could get you a 9. The old bio section had a level of inflation compared to the other sections and the new MCAT has done a better job addressing that.
At the same time psych/soc complicates things. In many ways its like another verbal section in terms of scoring and distribution. Everybody thinks the psych/soc material is easy and they have to create a scoring distribution so only X amount of people get a 128, 129 etc. On the scored FL the AAMC released, I know somebody who got 89% correct and that only amounted to a 128. For bio and physical sciences, that was good enough for close to a 130. So in many ways the addition of psych/soc is going to dampen alot of scores by it being similar to verbal. There are many many people who on the old test were able to ride out the fact they could ace the sciences and do merely decent in verbal and still hit 37+. But this new test makes that harder by diluting out hte weight the science sections carry.
For example 13/10/13 was a 36 on the old scale.
On the new scale if 130 is a 13 and 127 is a 10 well all of a sudden if you have a 127 in psych/soc you end up with
130/127/130/127: 514----equivalent to a 33.
Note I dont think either test is harder than the other. I took the new MCAT last year and thought it was at the level of old AAMC FL's and was a very similar test in style. But I do think there are people with certain strengths(ie acing the sciences, but only 70th-85th percentile caliber verbal performers) who this test will be harder for because of that psych/soc section which has similarites to the verbal. It was easy to separate the competition for the science section; it's not so easy to do so for the psych/soc.