Having gangway with an OSV vs. a jack-up barge is perhaps a matter of habit and what “feels” safe and familiar. Regionally, most of the WTW projects are in Qatar – Ampelmann has 7 out of 9 of A types there, which may be explained by the presence of Shell as an operator, who may be familiar and comfortable with this technology? Weather patterns of the Arabian Gulf is another area. There have been a couple of cases where system availably was an issue to due weather.
At the end of the day, these companies and people in those companies need to get used to it, and necessity is the mother of creation. So, perhaps, continued cost control and sustained low oil price may result in more adaptation of WTW in the Middle East.
As for the impact on OSV and backups… I don’t think it will move the needle too much.