People downplaying the Slimer movement on the premium/LE are crazy. It makes a huge difference that he moves left and right. Having put in hours of time on the pro, it will be very nice to wait to shoot for Slimer until he's in a safer position than just straight up the middle. He's going to take more skill to deal with overall as it's not the same shot every time. It's a very different experience.
The improved right ramp is also a big deal. The left flipper feed is nice, but really it's more of a reliability deal. The shot is VERY tight, and sometimes you'll hit it on the pro but not get credit because it doesn't go quite high enough. I had that happen several times. That right ramp on the pro is really cool how you can get more points for a cleaner shot, but it's a huge bummer when you make it and get zero credit.
The scoop versus the saucer on the right is also a decent improvement. Scoops are just more reliable overall. Saucers are fine, but they tend to reject at a higher rate, even on a perfectly clean shot.
The magnaslings are simply a matter of preference. They're more unpredictable, and they're not as active as regular slings, but they do bring some neat effect and randomness. The dead hits are present on the pro slings as well, but not as often as we saw on the LE stream. It's a different shape of sling, and it causes the switches to be less prone to firing on hits that are very high or very low on the sling. But there's no objective "better" between pro and premium/LE here.
The effect on the subway ramp can only be appreciated in person. Just like White Water, that insanity falls ramp is dang cool in person, but totally pedestrian in a top down video. The same goes for the Ecto Goggles. And yes, I've talked to people who have seen these in person and they very much back this sentiment up.
The bottom line is this: Both versions of the game are great. Tons of fun, great action, and beautiful. However, there are objectively things on the premium/LE that will make it play better and provide a richer experience. Whether or not those improvements are worth it to you is up to your opinion and situation. For me, it's worth it to go LE, but that might not be the case for many others. I don't think the pro buyers are "settling" for less, but premium/LE aren't overpaying for features either.