If you're trying to figure out if you should keep a premium or a pro, you can't make a bad choice. I have a pro and my buddy has a premium. They're both awesome.
The hammer isn't for everyone. Personally I don't care for it because I don't like how it looks. I think it's a great mech with a dumb casing. It doesn't slow down play for more than a few seconds. The only thing it might do is save you from draining on the lock shot.
The snake holding the ball on the premium is cool. Again it only makes things a tiny bit easier because you have less balls in play on occasion.
The spinners are cool, but don't add a lot to the gameplay.
The cross raising out of the ground is meh.
The light show on the premium is much better than the pro. You miss out on a lot of cool lighting effects when playing a pro.
All in all you won't miss those things when you're playing a pro. The gameplay is so good you don't think about any of it.