I'd say both Tylenol and Ibuprofen usage is common in ultras. It's not cheating.
Generally Tylenol is safe if it's used within the dosage on the label. It's easier to overdose on Tylenol than Ibuprofen. Ibuprofen can be harder on the body and can increase possibility of Kidney damage and Rhabdo.
Obviously, I'm not a doctor so you'd be a fool to listen to me here. My personal choice though is to carry Tylenol but I'm only using it for an unplanned problem. Imagine me falling and hitting my elbow. I might use Tylenol then. Painkillers are not a part of my plan though.