Hey jyossarian - I've got a Nexus 7 in my Swift folder from Peter Reich. I just had to go to Edinburgh, Scotland for a few days and took my swift (kept it in hotel rooms, took it into offices and bars, cafes without a problem :-).
Edinburgh has a *lot* of (to me) aggressive hills. The hub gear worked fine; I think 1st+2nd worked really well for my legs on the uphill, and 6/7th fine for long downhills. Mind you, if you're in a very hilly area I read that the Nexus 8 has a larger range?
I recently bought some Ergon MR1 grips
http://www.mtbr.com/reviews/Grip/product_125006.shtml - they really helped on the climbs - also got rid of some discomfort I was getting from normal grips. They cut easily, so I took an inch or so off the right grip to give space for the Nexus twist changer.
I did have some problems with the gears 'slipping' into place occasionally, but it was because the tension was out on the shifter - a quick twist of the cable holder to line up 2 red dots on the gear and all was well.
I personally don't see the extra weight as a huge problem...you can cut weight from other parts of the bike...the seatpost and saddle grip seems pretty heavy - I wonder whether Peter does 'special' seatposts?
For me, the ability to change gears whilst stationary, the simplicity, lack of maintenance and messy mechanism sticking out of the side of my bike more than compensates for the extra 2 lb.
I personally don't like the twist gear change - I find it a little uncomfortable at times. It may be just a 'getting used to it' thing. Anyone know if you can retrofit a normal shifter to a hub gear. I suspect no. It's not a major negative for me, but is the only negative I can think of about the Nexus.
Only thing I am going to change on my swift is the length of the handlebar stem, for me personally (I'm 5'11), its a little short and I find myself sitting past the back of the saddle...but that's a $20 fix and a 5 minute unbolting exercise.
Btw, has anyone seen any bike couriers in NY riding a swift? I would have thought they would be the ideal courier bike, as they're fast, sturdy and can snap in half in seconds to get in a lift etc?