Thanks for the links - had a good read around - and the first few sections of the text itself. Interesting - though I was (I confess) beginning to tire of the repetitive nature of the structure and telling. Likely not fair after only reading about 7 sections) I don't particularly feel it has such an odd structure - different, yes - but no so unusual. Perhaps if I read the whole, I'd feel differently.
What I meant by scratching an intellectual itch were some of the more mathematical or random constraints - like leaving out the letter e. I suppose it might produce more thought to produce quality while avoiding it, but if the same amount of thought was exercised while using it, can't see the communication benefit.
The value of any writing, if it's written for an audience, is the reaction of that audience. Don't suppose it matters how anything is written so long as the audience get something.
BTW: the example you gave - the city and string. I've 'suffered' a related idea to do with geographical relationships for years. Spooky. Still, glad to know I'm not the only one who has odd ideas.
You might like Cloud Atlas (David Mitchell) plays with time and idea threads in a very interesting way. Unconventional in many aspects - but sections within the book are often linear. A very good read. (I thought)