Perhaps the only reason you'd replace the arm is for weight (though, I've never held one to know) coz apparently, the HPA arm is lighter. But unless you're counting grams to shave off for lap times, stock arm FTW.
Haven't kept up with that topic, but I recall someone [more mechanically knowledgable] said that the pivot point in the stock and most aftermarket arms are there for a reason, and the RE arm being solid "could" cause issues like what's been documented.
Someone also said the stock arm with a PF...