Your point on expensive oil is well taken, as an engineer I have to wonder why the Speedhub wasn’t designed for normal gearbox oil. (Probably too thick - both me and the oil!) The special oil costs £8 to £12 a year (A rip-off agreed!) The only other maintenance is to change the hub cable every 3rd year (£5) that is it!
From the Rohloff site:
"After approx. 90.000km, a Rohloff SPEEDHUB 500/14 was sent back to us (Rohloff) in order to be inspected. The customer wanted to know exactly what sort of a condition the mechanism was in after such use. After a thorough examination of all the internal bearings and gears, the service mechanic could not find any signs of extreme wear or function failure."
That’s 51 miles a day for 3 years! How many derailleurs would this person of got though in the same time? Plus the extra chain wear + the rear clusters etc. I would surmise that the Rohloff works out cheaper for in the long run.
The jockey bolt it is only one of a dozen plus specialist parts that would be very hard to replace OR mimic (see
http://cycle.shimano-eu.com/media/cycling/techdocs/en/bikecomponents/RD/EV-RD-M760-2269_v1_m56577569830494493.pdf). All these parts are siting exposed to the elements.
The derailleur has another major weakness it relies on a straight derailleur hanger. Although this is repairable - even in Mongolia - why relay on technology that is so fragile and so exposed to anything that wants to destroy it. I have never toured in a sparsely populated area like Mongolia but if I did I wouldn't be expecting to be able to get hold of a brake cable never mind a derailed.
In engineering I am a great believer in maxim KIS (Keep It Simple) Now the Speedhub is complex but it simplifies the bike, makes the bike easier to ride and requires almost no maintain. All the complex parts are protected from the environment. A derailleur is not as complex BUT it requires looking after and doesn’t have the longevity of the Speedhub.
The Rohloff Speedhub is an Aston Martin in the making! I explain. 75% of all Aston ever made are still on the road today. I bet the same will be true of all the Speedhub ever made in 20 years time. Just like Astons, once you ride a Speedhub you don’t want to ride anything else. Unfortunately just like an Aston it isn't cheap.
Anyway as my granddad used to say ‘You pays you money and you takes your choice.’
Wish you happy pedalling
Stutho