Here's a comparison shot of the 3 generations of the Stretch.
To me, the blade shape changes between them have been minor and inconsequential. The Stretch 2's choil is both larger and deeper than the two previous versions. It does feel a bit more secure to me, although I'd agree with BFK that even deeper would have been nice. The handle is definitely longer. That was a disappointment to me, as the older ones fit my hand perfectly, so this one just takes up more space in my pocket. However, I have fairly small hands so I'm sure it will increase the number of people whose hands it fits.
Took me a while to get use to the differences, but I'd been carrying one Stretch or another almost every day for the past 11 years. Peel ply G-10 is not my thing, but this customized version has seen it's share of pocket time....
...scales are textured Black Palm, by Steve Sketchen.