I would say a dramatic role
can cause an actor to lay his soul on the line more. I wouldn't say that everytime. And I'm not just trying to be devil's advocate here, I swear.
I think if you read any Jim interview in relation to the wonderful 'Eternal Sunshine' film, it's clear to see there was an awful lot of him in that performance. His experiences moulded him for that part and gave it gravitas.
However, I don't believe that of all actors. Some can just use that old idea of 'acting' and don't personally lay themwselves on the line for their part (remember that old story about what Larry Olivier said to Dustin Hoffman whilst filming 'Marathon Man'....).
Just wanted to add that.
I believe we do look into Jim a little bit more each time we see a dramatic role...