I have stuck mainly with 175 to 177 and I am finding the opposite is true for these weights compared to most Gold Line versus Opto. Take into consideration that it is easy to turn a River, but I find it harder to turn a really heavy Gold Line versus an Opto.
Now, I have not often looked, nor cared, about PLH so I cannot comment if that had a factor in why my Gold Lines seemed a touch more stable than my Optos, but I can say this that all four of my 177 GL Rivers are from different batches. My most stable one is from the first day we had it in the store which is not even noticably different than the one I just bought three weeks ago from a "competitor." Even the Color Shift River I purchased two weeks ago has close to the same stability.
The only reason I keep my Optos around is because they are the best one-disc night disc ever made. I played a 151 hole marathon last January and the River was a God-sent, especially since I needed to keep moving to keep warm and did not feel like lugging around more than one disc.