Thanks for the replies. @JesperXT thanks, good to know
@Cranky It's for a pompetamine, which is 135mm OLD. I do have some flexibility with the sproket on the hub, so I can hopefully fine-tune it. But not sure if I can get the chainline any lower.
@drøn that's a good point, but I was also tempted to make things more complicated for myself in the future: One reason why I thought about the alfine, or maybe go for a road double chainset, is to go for a double/double set-up. Something not dissimilar to this: there are 2 pictures of his/her chainlines (sorry for links within links. I'm not so hot at this stuff).
I was thinking of having rear sprockets of 21 and 17. And having front chainrings of 39 and 43. Hopefully with somewhat-functioning chainlines. And then I can chainge gear fairy easily*. I don't mind being a little off on chanline if it means slightly higher degradation of parts. I do mind the increased probability of my face hitting the dirt (or some other such painful malfunction), but but I don't really know what the parameters are for such happenings.
Also thought about White industries, http://www.whiteind.com/double-double/ but I'm incredibly (embarrassingly?) tight with money, so would like to consider less spendy options first. Also, I've already got these wheels, which have a free hub. But I might just start simple, get the bike on the road, and then think about overcomplicating things in the future.
Help and advice welcome. Derision and piss-taking discouraged, but tolerated if constructive.