Last Saturday, we towed a skiff in from Decision point. Recent honda outboard, probably 90hp, no kicker.
Yesterday, a fellow with a 2005 etec 225 went TU at the same place, and we were in the same neighborhood about a mile away. We turned to respond to his hailing but another gracious fellow helped him out. That made our trip, because the previous week, the last hour and a half towing meant close quarters combat with my two toddler boys after a long day, an early morning, poor naps, and towing past their bedtime. They'd napped better yesterday, but it would still have sucked mightily.
So, two tow opportunities in two weeks. Both vessels had later model outboards with good reputations for reliability (I'm not here to bash brands). But, both failed, and neither boat had an auxiliary or kicker.
We towed the fellow in at a little over six knots near slack tide. That's just about a half a knot faster than my 15hp honda kicker pushes my 26' hewes. So, on a like size boat with a like size kicker, return time would have been similar.
All this to say - concerns about the effectiveness of kickers in stormy seas is absolutely no reason to not have one...