Rotring 500

These are pretty nice mech pencils, but I'd get a rOtring 500 and/or GraphGear 500. I find them better for longer sessions because their gravity center is next to the lead instead to the back of the pencil. Also, if you're going to use them to make technical drawings, It could be a good idea to get one of those slim erasers like Pentel slim hi-polymer or Tombow Zero (pen eraser, or w/e that's called).

However, if you've got the "itch" to try other pencils, here is my advice: if you like the look of the Rotring 600, get the Rotring 500 instead. The 500 is lighter, better balanced, and typically costs half the price.

The Rotring 500 is about perfect since the plastic body combined with the metal grip section bring the balance closer to the tip. I would like to try a Rotring 600 2mm lead holder, but have never had the opportunity to see one in person, but my curiosity isn't sufficient to overcome the price tag.