I mean, I'm one of the developers of CIAngel, so that gives me a bit of insight. I've also looked at the source of most of the other CDN downloading programs out there too.
As I've said, there's no identifying information sent when you use
3rd party apps (CIAngel, FBI, PC-based applications). I have no idea whether the eShop itself will send your NNID off to Nintendo if you just install a ticket, then download using the eShop, but my guess is it probably does.
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The "ticket" method (TikDevil, Ticket Install mode in CIAngel) is what you're thinking. But you also get that exact same ticket if you download the CIA and install it directly on your 3DS. The ticket is just part of the whole bundle that allows you to re-download the game from the eShop later.
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Why bother downloading the CIA on your PC (And having to set up Python, FTP/card reader, blah blah) when you can just download and install the CIA at the same time directly on your console with CIAngel?