I have a 710
Fits my hands perfectly. Great cutter.
It was also my first Benchmade, I wanted to get one that had G-10 handles, looked good, and had good edge geometry for all around cutting. I had a chance to compare just about every model at my local shop and the 710 won outta all of em. There is also a lot of information on it because it seems to be one of the favorites for people to review
G-10 is a hitech plasic, but very high quality, durability, and grip.
The M2- D2 chemical comparisons are in the FAQ section of the forums.
They are both good tool steels for cutlery, they are not stainless, but they come with a black coating that protechs them from rust (but does scratch)
It is a high quality production knife, with good ergonomics and materials that can be found at a pretty reasonable price. And there is a smaller version availible 705 for people who think it is too big.