The Downtube NS is shorter frame. Wheelbase is about 39", or 3 or 4 inches shorter than a road bike and even other folders. How tall are you? I'd be concerned about cockpit room and stability under speed.
I am a roadie also and had previously bought an NS for the same reason as you.
The Downtube Front Suspension was a nice frame. If you swapped out the front fork which is very heavy and not necessary for road riding, then upgrade the drivetrain, you'd have a very good bike. This is what I did.
This was taken before I swapped out the front suspension forks.
SRAM X.7 drivetrain off eBay. Great upgrade for low cost:
