I have the pro, love it, never looked back, no thoughts of trading up to an LE, to each his own. Has zdoor's cube mod, led color matched inserts and all the necessary tweaks. Plays great. I didn't think the LE was worth over two grand more and instead used that money to buy another machine (hs2, which is now gone).
It's a fan layout, which makes it different from most of what I own. Have to admit, when I start playing, it feels like there is a lot of work ahead, but once you start hitting the shots, you really start to get into it. I have all avengers set to medium or hard.
I have a sub hooked up to it. Not sure about the LE, but the only time a shaker really does anything is on hulk mb. I didn't think it was worth it. Sub on the other hand really brings out the sound, and there's a lot of good sound on the game.
With family arcade selling his at 5k, the gap has definitely narrowed. I'd think you can pick up a really nice HUO pro for under 4, maybe 3500 if you are lucky...not mine of course!
With IM coming soon, this game along with xmen makes a really great combo!