Derailer systems are open to the elements--I like the Model T analogy. That means that these steel parts get wet. They get dirty. Because of that, they need regular cleaning and adjustment (unless you don't care about missing some gears or skipping gears when you shift).

Further testimony--go check out well ridden derailer bikes of school kids. See if they operate well. Half of them don't even use the derailer. I have three teanagers--two with derailers. One can't even operate it, they other doesn't try. His chain fell off once.

So, it is disingenous to say they require very little maintenance. They also are more difficult to operate as you must make certain by looking that the chain has shifted. You have to regulate your speed, look, hold the shifter for the right time, and proceed. Also you have two shifters, going in different directions. The one operating the big cog is a challenge to shift for some.

On the other hand, the internal gear hub is a simple shifter with nothing to look at (no chain to see engaging) that comes with a chain guard to keep your chain clean, is reliable, and needs no adjustments. I'm sure it needs some maintenance, but I haven't done any yet.

While it is obvious that Interested far prefers the derailer and sees no benefit to the internal gear hub, I see the exact opposite conclusion!

Keep on cycling,

Dave