You don't want to be out in big waves if your big motor quits. You want to have power to maintain direction and handle the waves with good throttle response in a smaller boat. A kicker can get you home on a normal day but won't maintain good boat control in the waves. I wouldn't go out in over 10-12 knots or 20km winds if you may have to rely on your kicker. It also depends on whether the wind is building or dropping. I'd rather go out in big rollers from the night before with the wind dropping than a moderate chop that's forecast to pick up significantly. The waves aren't as big a factor when your fishing, other than your anchor holding, it's the run out and back that can be rough depending on distance.
I have an 18' tiller with a new Evinrude 60hp HO. I find the tin boats ride higher in the water and don't plow in as much as a glass boat running in waves, but they ride a lot rougher in a moderate chop. Your hull design is also a factor, width to length, weight, deadrise and reverse chine or not all play a factor. As has been said get a good feel for your boat before you push it. There are enough nice days to be not worth risking it if you're uncertain.