From what I understand, tradition says that the Disciple John was exiled to the Island of Patmos. Would this have been an inconvenience or a major hardship?
John exile to Patmos was a way to get rid of him. They tried killing him by immersing him in boiling oil, but God preserved his life. I think more out of shock and fear, his Roman captors sent him to Patmos to keep his influence away from the populace.
Here is a brief description of the conditions on Patmos in White's Book, Acts of the Apostles.
Patmos, a barren, rocky island in the Aegean Sea, had been chosen by the Roman government as a place of banishment for criminals; but to the servant of God this gloomy abode became the gate of heaven. Here, shut away from the busy scenes of life, and from the active labors of former years, he had the companionship of God and Christ and the heavenly angels, and from them he received instruction (p.571) for the church for all future time.
While his surroundings might (p.572) be desolate and barren, the blue heavens that bent above him were as bright and beautiful as the skies above his loved Jerusalem. In the wild, rugged rocks, in the mysteries of the deep, in the glories of the firmament, he read important lessons. All bore the message of God's power and glory.
Though I'm not sure it's relevant, for full disclosure the author was a Seventh Day Adventist Christian.
From Lexham Bible Dictionary entry on Patmos:
PATMOS (Πάτμος, Patmos). A small island in the Aegean Sea off the southwest coast of Asia Minor (Rev 1:9). According to a tradition preserved by Irenaeus, Eusebius, Jerome and others, John, the author of Revelation, was exiled there in the 14th year of the reign of Domitian and subsequently released to Ephesus under Nerva (96 AD).
Answering @DJClayworth about the Christian group: since Irenaeus was born in 130 AD and Tertullian was born in 155 AD, and since the tradition seems to established among the early church fathers, the Christian group believing this tradition was the catholic pre-Constantine group.