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You say that there are clearly some performance considerations if operating to Class 1, but not so significant if operating to class 2 (apart from the pilot 'clenched cheeks' factor to helipad type profiles). However, in most jurisdictions once one has reached DPATO it is still necessary to have performance Class One en-route either at MSA or at 1,000 feet above the take off elevation. In some countries this is 150 fpm RoC and others, 50 fpm RoC on one engine at intercontingency rating (older types) or MCP (newer types) with landing gear up and Nr at manufacrurers optimum figure for that configuration. The companies I used to work for used either the single engine en-route performance or some variation on twin engine HOGE performance (e.g. HOGE or HOGE + 500 feet), whichever was the more limiting, to limit take-off weight from offshore decks or helipads. For the types you mention, the 365N or 365N3 at sea level on a 30 degree day, this would translate in the case of HOGE at sea level, into a restricted take-off weight of 3,900 kg in the case of the N or 4,300 kg in the case of the N3. Notwithstanding the higher basic mass of the N3 and its higher fuel consumption, this translates into a considerable increase in payload. The difference in figures is similar for S76A+ versus S76B or S76C+. (Actually, the S76B is a lot better, but is a real 'gas guzzler').
You say that some older aircraft make there way into Africa where the less competitive market and demand for class 1 does not dicate the latest and greatest (and therefore most expensive) aircraft. However, in West Africa, where the majority of helicopters are operating in the offshore oil market, the opposite is the case. The oil companies want the latest equipment, the market is very competitive (especially between Bristow and CHC) and some governments (e.g. Nigeria) will no longer allow an aircraft more than 18 years old to be imported into the country. It's for reasons like this that in Equatorial Guinea, Cameroon and Nigeria you'll see lots of Bell 412s, EC155s, SA365N3s and S76C+s (with more old 365Ns and Bell 212s being replaced every month) and CHC shortly to start operating A139s in Nigeria. Bristow is replacing all the old 212s with 412EPs in Eket. I think it's actually more in Europe and the Caribean that you're likely to see the old aircraft these days!! I wish I were still in Nigeria - I'd love to try out some new toys!!
