Actually it’s the other way around. The Inpact kit is the original model. Later Pyro, then Lindbergh offered the same model. Those biplane kits are pretty good considering when they were released. I have the Fury kit as well, waiting for another day. I want to pick up the Fairey Flycatcher and the Bristol Bulldog kits when I can find them.
The exterior of the Gladiator is not as nice as the Roden kit, but with some work on the interior, and some cleanup of the exterior, the kit can still be quite nice. Best thing going for it is the price. I got it it for $5.00. And a friend of mine gave me the Roden Sea Gladiator kit for free, so I can build a pair.