as a visitor - Never buy round trip
as for stressing out over the ferry service - Manpot may correct me/remind me otherwise... but.....
In over 10 years.... I've never missed a boat due to it being oversold
I've never had a visitor miss a boat due to being oversold
I've heard of it... but never experienced it
Maybe, possibly.. it could happen, perhaps in March or thereabouts
Then again... I've heard a lot of "stuff" on island over the years.. a good deal being hand-me-down, fourth-hand, or invented nonsense from bored people
The reason for not buying round trip... ferries often get cancelled - due to mechanical breakdowns
But, the competitor (usually) picks up the slack and (often) honours the tickets from "the other guy"... especially if there was a breakdown
As for the ferries... in my view, and the view of my visitors - arriving by ferry is one of the "wonderful, unique entrances" you can make onto the island
It bugs me when people slam the ferry services
Yeah - they ain't perfect... but, this is all part of island life
Your mileage may vary... I guess much depends on why you come to this particular place on the planet
