I've played both ways for 35 years. Although tone plays a part, I find that certain rhythmns are achieved by the the up and down action you get with a pick that just don't happen with finger style. It's not a speed thing, but a different rhythmic emphasis. And of course, nothing rocks like straight downstrokes!
And having just started with a 5 string, I realize I haven't yet used a pick. I'm gonna try it today!
