Lex, keep in mind that all designs are a compromise. The EP600 and EP800 are very large box subwoofers tuned to hit very, very low notes found in HT soundtracks. Musical passages rarely get much lower than 20 hz though, which the EP500 will reproduce just fine. IMO subs tuned to hit those really low bass notes guve up a bit of the upper portion of the bass range, say around 60 - 80 hz... which is the range that you feel in your chest. Those notes below 20 hz are the notes that shake things like furniture, dishes, windows, etc... but you don't feel those notes pounding through your chest so much.
So it becomes a question of what you're looking to use it for. Do you listen to a lot classical music, and watch a lot of movies that you really want to squeeze the maximum amount of low end notes out of? Or do you like to listen to bass heavy music that pulsates throughout your body? The EP600/800 would do great for the former, while the EP500 might do better for the latter. Keep in mind this is only an opinion of mine since I've never heard the 500. But I do know the EP800 very well, and I would have to say that I feel it gives up some intensity of those upper bass notes to bring me the full compliment of lower bass notes.
And Dakkon, I know what you're talking about when it comes to sound pressure. However I must say, if I'm listening to my music here in my seat 16 feet away from my M80's and I get up and walk over to 1 foot from them, they will sound louder. It's not 10 times louder, but louder just the same.
I can remember the very first concert I ever attended.... Motley Crue's 'Girls, Girls, Girls' tour, at Market Square Arena in Indianapolis. Me and my buddies were sitting in the very top row of the stadium to the right of the stage. The music was incredibly loud up there (they got fined for exeeding safe concert audible levels on that tour). So this tells me that sound pressure does have something to do with it. But I'm also sure if I was one of those people sitting in the front row right next to those speakers, it would have been even louder!
