Finally got my hands on the Shadow Fox. Dug out the old one for comparison. They're pretty similar in size, although the new one is sharper and more streamlined (mostly due to, y'know, not having a wind-up motor in the torso). The new one also seems to be a slightly bluer black than the original's grayer black, but that could just be my original being a bit faded from years out on the shelf.
A couple notes about the build. First, some of the pointy bits (ears, claws, especially the teeth) are sharp enough that a little caution is warranted. Second, the housing for the mid-torso joints (the first part of step 14 in the instructions) is prone to popping apart if you're not careful when handling those joints. I glued it together, it's fine now, but anyone else building one might want to just glue it while building to save the trouble of having to take it apart to get to it later. I also glued in the small net launcher inside the tail, the tiny tab wasn't strong enough on its own when moving the barrel, but that's less of a hassle to get at. The spoiler-ish flap over the hips is also kind of easy to knock off if you're not paying attention while moving the tail.
Other than those mostly minor issues (the mid-torso joint box is the only one I'd consider a real problem), it's a pretty solid build with plenty of articulation. The main gun still has the original's extending gimmick to rise up and aim around, and there's a 3mm hole between the hips to put it up on a stand for running and leaping poses. It's a little heavy for a Figma-style stand, but a Bandai Action Base can handle it.