EESDL,
Unfortunately not true. Offshore probably a big company, regular landing sites, base airfield aids, no personal contact with customers, SOP's, BALPA (?), company cannot afford accidents. Onshore in the UK undoubtedly a small company, ad hoc sites/fields, pilot to customer/owner telephone calls especially regarding weather, virtually every flight different, easy to blame the pilot if things go wrong or the customer is dissatisfied, likely to be eased out if you don't fit in with company ways.
From experience of both I would say onshore "all weather" helicopter operations are far more demanding than offshore except for the obvious over water consideration, I have certainly seen the loss of more colleagues in onshore accidents than offshore.