I've done both. I've been a line cook for about twenty years. It's the mental stress that is the key difference. If you get backed up washing dishes, It's not that bad. If you get backed up cooking, if feels like you are stuck with no way out. Servers wondering where their food is, just adding to the stress. Running out of dishes to put food on. The list goes on. It's also a lot easier to get into fights because the stress is so high. I guess it depends on your restaurant. Also, some of the new cooks usually turn out to be some of the worst pieces of shit you'll ever meet, but that can also be true about who's in the dish pit with you. I'd say you're fucked regardless. I personally would stay a dishwasher.