I have used both for years.
I have an XT shadow derailer on my Swift. I want to ride fast, and up hills with it. I would not consider putting an IGH on it. My experience with a variety of them, they are a bit heavy, and I can most certainly feel the extra drag they produce. And it's a weird thing - once I have something light under my bum, it just wants to go fast. So the weight is a big deal for me - somehow it matters more than just the bare grams. It's not just placebo either - a light bike brings out more, I just have this urge to ride harder. A heavy bike feels more sluggish, even if the difference is slight, and it makes me relax a bit more, so I just go slower.
Re the maintenance - if riding in wet weather, the SA hubs are actually no good. Water got into mine every time, rusting the bearings. It is a helluva lot more work to strip and grease a set of bearings than to spray WD-40 on a chain, spin cranks, blow out with compressed air, and oil the chain rollers. And I have never bent a derailer on any of my folders with them on.
I also have doubts about the validity of the argument that a low-hanging derailer will pick up extra dirt. If you are riding normal dry sealed roads, I don't think there is any extra dirt. On wet roads - sure, but I have found the majority of wet dirt is splashed up from the wheels, and smaller wheels tend to splash more than big ones, so the smaller wheels make the derailer and chain get dirty quicker, not the low-hanging position per se. But in very short order the difference between small wheels and big wheels is gone because the chain gets saturated. So I find that the chain gets as dirty as with any sized wheel bike. I don't notice any difference.