The Polywebs have a thicker coating and feel waxy - it is this that gives a more mellow tone and less string squeek. The Nanowebs have a thinner coating and sound and feel close to normal (uncoated) strings but have the capacity to last much longer tonally, ie they keep their brightness for significantly longer.
Bob
Interesting post. I have always allowed a bit of excess (in line with your suggestion) when winding and always put a right angle bend in the string for going through the post. The strings that usually break at this point are the 2nd and 3rd which are under a lot of stress from altered tunings, but that is what I would expect. If any of the other strings go, it is usually at the saddle, though I do get breaks on the 2nd and 3rd here too.
If I gigged really often, I would use D'Addario and change them each time, Elixirs would be too expensive to do that. However, I don't gig more than about once every month (on average) so I use Elixirs for the longer lasting tone, but always change for a gig to minimise string breakage on stage.