Never handled a Scallion, but I like my Chive. The Scallion looks like it's the Chive grown by about 15% in all dimensions. If the Chive is any indication, the Scallion should be a great little flipper. As for Kershaw's 420HC, they do as good a job as any with it. Buck has a good reputation with their 420HC, and my Blur in 420HC holds up just as well as any of my Bucks. It's also easy to sharpen (if you're good with recurves). If you haven't checked out the Leek, that's a great one too (one of my favorites). Commonly available in 14C28N, CPM-D2, and S30V varieties, if you prefer a different steel. +1 on the recommendation for blems from Kershawguy. Great prices and great service.
The Flash 1 is also a nice little knife. Because of its narrow handle, it's sometimes a little awkward to open using the thumbstuds if you don't have the right grip on the handle (the flipper on the Chive, and presumably Scallion, grip and reliably fire every time). Also the contours in the finger choil are a too small for a knife that size (fine on the Flash 2, but they could have done without them on the 1). I do like the deep pocket clip and that it really disappears in the pocket (small & lightweight).
The Flash 1 is also a nice little knife. Because of its narrow handle, it's sometimes a little awkward to open using the thumbstuds if you don't have the right grip on the handle (the flipper on the Chive, and presumably Scallion, grip and reliably fire every time). Also the contours in the finger choil are a too small for a knife that size (fine on the Flash 2, but they could have done without them on the 1). I do like the deep pocket clip and that it really disappears in the pocket (small & lightweight).