I've been a Newport guy since my Mil-Spec from 2001. Still roll it on occasion. Got a GSS Newport 2 with square bumpers some time back. One that matched Tiger's gamer, lefty. I loved it. Feel was amazing. GSS is SO soft! But damn if I did not lip more putts with that thing then make. Then I compared the Newport / GSS NP2 during some rounds and was much more consistent with the rounded bumper look at address.

So like you, got a new one after so long and got less consistent. Since I traded the GSS, I have picked up a couple cool tour lefty sticks that are also Newports, this time with sound slots/beached. Putting is a feel game. You should roll with what gives you the most confidence, period.

To better answer you though. Go to your local pro shop / box store with selection of putters to try. The pro should be able to help see what suits your stroke the best for your game.