Igo,
I've got a Russell DayLong on my NT. I had one on my Connies and loved it. I love the way it feels and rides on the NT. It did raise me up about an inch. Where before I could flat-foot the NT with both feet, albeit with less weight on one foot than the other, now I can get one foot down flat and touch the ground with the toes of the other foot.
But, that's OK. The seat works very well for me.
BTW, when I first got the NT, had some issues with the reach to the bars. MC Larry's bar risers helped, but more than anything, just putting on a lot of miles made the biggest difference. I was mostly comfortable on the stock seat. It didn't bother me at all on my Saddle Sore 1000, but on a couple of 800 mile days, I had intermittent periods of butt burn.
I'd recommend riding the bike a bit before I did much in the way of drastic changes. However, I would go ahead and get the bar risers from somebody it I were you.