If you get the 440 then absolutely get the 840 earpads. If you use them outside too, also plan on getting the straight cable, because stock, they come with a 10 ft coiled cable. Even the straight cable is a bit long and when I wear them out, I end up looping myself with the cable, which works out okay when you layer up but otherwise gets cumbersome. I wear them while doing work in the backyard though so it's not impossible.
I LOVE my Shures. I don't have a lot to compare against but it gives me nice clean bass, and clear mids, and nuanced highs. I'm starting to re-listen to a lot of my songs and I'm starting to discover harmonies that were hidden by bad drivers or cheap headphones/earphones. Snaps, claps, cymbals, and chimes also have emerged from my music. I have PC speakers that run about the same price and the sound from the 440 is considerably better - just to give you a frame of reference for what I'm comparing to.