I was just thinking about what LE models had gameplay differences and no Premium model. I was a bit surprised by the numbers made of each model:
Avatar LE 250
The Rolling Stones LE 350
Tron LE 400
Transformers LE 750
X-Men LE 550
Of these games I don't know which one have bigger gameplay differences than others. I can't really remember much on Avatar except for the power ball. All the other things I remember were more cosmetic than gameplay (coffin opened, mech stomped a little more). The Stones had power ball, an extra song, magnets under the playfield and the save posts. That seem like quite a bit of changes gameplay wise. Tron had drop targets and an extra mode. Transformers seemed to have the most differences. Both upper corners are different and the drop target in front of the scoop. X-Men has the Nightcrawlers, spinning disc and moving ramp.
It looks like Transformers taught them a bit of a lesson on how many LEs to make. I wouldn't have thought that 750 was a crazy high amount since there was no premium, but since they are still readily available from distributors....I would say they over estimated. I'm also guessing X-Men got 550 instead of the originally planned 500 just to entice more people to buy Magneto versions (make Mags more rare to make it more desirable).
Anyway....in summary. I would consider Tron LE a bigger grab over Metallica LE because of the lower numbers and the fact that it had no premium. Having said that...I would take a Metallica pro over an Avatar LE.