Finally got some time on a Pro model. There's some notable differences and some less than notable ones. The Pro can plunge into the pops for a skill shot and some easy multipliers. The Premium cannot do this. I got as high as 11X on one of the first games with Turtle Power Multiball, and the highest I've had on how many ever games I've played of Premium was 5X.
The diverter does absolutely change how you're able to play the game. I love the diverter and being able to pick your flipper. The Glider 'mode' is a cool little addition but it's difficult to score any meaningful points with. I wish the Pro had anything instead of that chunk of exposed and completely unadorned metal for the stopper on the ramps.
I missed the toy Krang hopping up and down while he was taunting you. I like the mech more than I thought. Purely visual and more theme integration so the value of that changes a lot by person
The two way spinning disc does change things but ultimately it's whatever as a feature. The Premium when loading up for multiball stops partway and spins the other way, and then does it again. If this was more random it'd probably be a bit cooler. Sometimes only spinning right, or left, sometimes changing directions.
I like the turtle van lock a lot. I missed it. It's got this 'oh man here comes all the Turtles' vibe that plunging one after another doesn't give you. More immersive to the theme, I think.
In the end they're both fun games which I think are quite a bit more fun if the theme is doing anything for you. If you can spring for the Premium I'd do it, but don't let it make you pass on a Pro.