wizwoz
I've never flown the classics, but I'll tell you that this was the first thing I noticed about this highly efficient wing. It just wants to keep flying. You'll find it surprisingly difficult to descend and decelerate at the same time in an NG cleanly configured. You can do only do one of these tasks well. For example, let's say your 250 clean in your descent and ATC tells you to slow to 210 kts. You'll find the NG loses very little speed even while it's slowed its rate descent to 400fpm in LVL CHG. And the "boards" don't help you very much either.
Here are the speedbrake numbers from my operating manuel...
Target Speed Rate of Descent
Clean/with Speedbrakes
.78/280 2100fpm/3000fpm
250 1700fpm/2300fpm
Vref40+70 1100fpm/1400fpm
As you can see, don't look for much help from your speedbrakes. That being said, let me say that the NG is a wonderful plane! It has many tools that allow you to think way ahead of the airplane, to the point of rarely using the speedbrakes at all. I arm them prior to descent, and forget about them mostly. You'll love it! Enjoy your training.