I've spent most of my a playing time on the Pro, and relatively brief time on the LE and Premium. I'll start out with this statement: The layout is different, smooth, and fun to shoot, and I would be happy owning a Pro, but if my budget was not the issue, Premium or LE would be my choice.
I think TWD Pro has the least amount of mechanical features and toys that Stern has ever released... two flippers, two bash toys and a magnet. That's bare bones even for a Stern Pro, but it's very fun to shoot and, and I don't feel the game is lacking when I play a Pro. That being said, it's clear when you spend time on the Premium/LE it feels like a more substantial game... there are more playfield toys, more mechanical features, and colored inserts alone are always a good excuse for the upgrade (and a shame Stern chooses to keep them out of the Pro). The LE is my favorite model.
That same thought process applies 100% to ST, and to Tron. Even though the Pro has all the same general game play, the Premium/LE also have that "je ne sais quoi" that makes it a compelling purchase over the Pro... And as long as Stern insists on releasing the "director's cut" version on only Premiums and LEs, be thankful there is a Premium for TWD and ST... with Tron you have hoards of disgruntled customers like Eli spending massive amounts of time to replicate and make available the Premium features (lighted ramps in this case) that Stern is contractually incapable of selling to customers regardless of demand. Cosmetics can't always be understated.