I'm really GAS'ing for a DL4. I've got a couple questions. What does the expression pedal do? Should I get it? Oh yeah BTW, if I did get it, it would be used of Ebay. I find the $250 price tag a bit ra-donk. Also, does anyone here use an AM4, DM4 (also considering), FM4, or MM4? What do you use them for? And one last question. Would you reccomend a Big Muff or DM4? EDIT: Looking on the Line 6 website, it says the DM4 has a Big Muff setting. Any experience with this?