PS is supported by subscriptions just like CR. So...there is no inherent bias in their reviews and they can be trusted from that standpoint. However...no one can be experts in everything and they have considerably less resources and staff than CR to conduct their evaluations so I would not treat their findings as gospel or necessarily scientific though they try their best I am sure.
In a past life I had the opportunity to "interface" with the folks at CR regarding their testing procedures and conclusions in a couple of different but related product categories. Even with all their resources...their results were badly skewed from what industry and expert testing would have produced. As an example...one product I had been intimately involved with was given their BestBuy rating when by DESIGN it had been created to be somewhat innacurate (but more saleable) by ME! I laughed all the way to the bank as customers took their rating as gospel.
So...learn what you can from the detailed reviews of the products in PS...it is the only place you will get such info...but be wary about trusting the final ratings too much.