Only choice now is which Dynamo. Do we have any idea of the expected service life of the N72. I am also interested in how the output at low speed compares between the N72 and the Schmidt, I seem to have a habit of putting M.C Escher styler routes together that go eternally up hill, with all the camping gear on board that means average speeds are usually pretty low, i therefore need to know that it is going to provide a reliable charging platform (my main interest in a dyanmo, not all tht bothered regarding lights, view them as being a bonus). Andre, when you say " I have both and the the Shimano clearly comes onto full song a bit earlier" do you mean that the resistance increases, or that ouput increases earlyer (or both?)
Mark, I've seen 40K and 50K, kilometres, quoted for the expected life of the cheapest Shimano dynohubs. A SON should last twice as long. The more expensive Shimano models should last as long as an Ultegra hub. Very few cyclists will discover whether any or all of this is at all precise.
What I mean about the Shimano v. the SON is that the Shimano delivers more current earlier. I'm a slow rider too -- I chat, I live in hills and on a hill, and I regulate my riding by my HRM, not my cadence -- but I like seeing a lot of light on the road from my lamps. The Shimano delivers perceptibly more light (= current for any purpose...) than the SON up to about 18-20kph, which is around 12mph.
You can ignore what you hear about the Shimano having more drag. Those numbers were taken when the Shimano was a jumped-up Sanyo dynamo and have nothing to do with modern Shimano dynamos. For practical purposes you will never discover even in side by side tests whether the Shimano or the SON has more drag; we're talking like about a foot of elevation every kilometre for either of them. Not worth discussing.
***
Actually, if you think about it carefully, for a tourer in rough places, these relative mean time between failure questions are not necessarily the most relevant considerations. For someone who, like you, effectively isn't on a budget because you only wait a little longer to fit whatever component is necessary or desired for a good reason, the relevant question is, "How much will you pay for the highest available security in your dynamo?" In that aspect, the Shimano and the SON are both unlikely to fail, but the SON is, say, twice as unlikely as the Shimano to fail. If I were touring in the Australian outback, in Africa or South America, or in the more desolate parts of the United States, or anywhere in Asia, I'd argue that my life is definitely worth the extra hundred spondulicks or whatever, and I'd fit the SON, and consider the difference in price cheap insurance. Where I live (in Ireland, never further than a few minutes from people), that statistical argument doesn't hold much water, so the Shimano is more than adequate, possibly even preferable for being better matched to my needs.
Andre Jute
