Yeah man I really dig Stevie Wonder, Marvin Gaye, James Brown, Otis Redding, Sam and Dave, Sam Cook, and all those cool cats, lol.
Not Motown but along the same genre lines I've been listening to the Impressions (Curtis Mayfield's first band), Sam Cook, and the Isley Brothers. Modern soul, I'm really into Erykah Badu, John Legend, Amos Lee, and India Arie.
The guitar parts can be so simple and so complex at the same time. You really gotta be in the "pocket" to get that feeling.
The only Line 6 pedal I've used is the DL4, got rid of it after I got my Echolution. I actually wish I had it back, has A LOT of useable sounds on it. I hear a lot of guys in the area getting really cool sounds out of them, but I also know I had to replace footswitches on it more than once, and have heard similar complaints from lots of people. But I might buy one again just to have.