Well, I see three down sides to the feather rest. One is the tendency to collapse when wet. Two is that it places the arrow further above the bow hand, which is generally considered bad for instinctive shooting. Third is that it will wear out in time (maintenance item). That said, mine on my Kodiak has proven to be long lasting with a few thousand arrows shot and no visual sign of wear.
Like I said before, I believe the shelf design on the PL gives much of the benefit of a feather rest as it is, being curved.
If you do try it, I’m interested in your experience.