I don’t have the expertise to offer any sort of comparison of the models you mention, but I share your problem of living a long way from anywhere I could try any of them and do own one so can let you know my experiences with that particular recorder. I should also say I am not any sort of expert, so this is just my opinion.
I was in a similar position to you: playing a plastic alto and wondering what a wooden one would be like, and after looking around a bit, bought a Küng Studio in pearwood. There is something nice about playing a wooden instrument – it feels like that’s what recorders should be made from, and I do like playing the Küng. To be absolutely honest, though, it is not a better instrument than my plastic Aulos Hakka. I bought the Aulos on the basis that lots of people recommend it as the best plastic alto you can get (their comment, not mine! – I know lots of others have their enthusiastic supporters as well) and, though expensive for a plastic alto recorder, it’s a fraction of the price of even a cheap wooden one. It’s often easier to get the high notes on the Hakka, and it doesn’t clog as easily as the Studio. Sometimes when I’m trying to come to grips with a hard piece I give up on the Küng and switch to the Hakka because I don’t get the failing high notes.
On the plus side, the Studio is attractive, seems very well made, is substantially cheaper than any of the others you mention, and has absolutely standard fingering. All the common alternative fingerings also seem to work on it, whereas I’ve found a couple that aren’t so good on the Hakka. I can also confirm that it does not need oiling, it’s treated with paraffin internally so is pretty low maintenance (though some people advocate oiling all wooden recorders). You can download the instruction manual from the Küng website.
The Moeck is nearly half as much again as the Studio, and the Superio is almost double the price, so they should be better instruments than the Studio. And just a thought: you might consider a Mollenhauer Denner as well – they cost about the same as the Moeck and some people really like them.