Jayjay, You've actually noticed a performance increase? I find that a bit surprising, though I'm sure it's because you use the advanced features of C2. I have had to work around some of C2's limitations to make map creation, storyboard editting, and visual scripting possible in my game, but performance is still top-notch on my crap laptop. So, there's ways around things in C2, it's more a matter of whether you find your time well spent making work arounds. In my specific case, it is, because I can easily add new functionality using the easy interface of C2's event sheets and the level of control over Behaviors.
I've ported my first map and some gameplay functionality over to UE4 though, and there isn't really a performance difference. But I'm running 60FPS either way, so that really doesn't mean anything at all.
Though, I really do think it's a good idea to bring a 2D game to a 3D engine. That's why I'm making the fist BSH in C2 (so I can get it done quickly), and the next, BSH 2 is in UE4. The UE4 version is basically just a 3D adaptation of the 2D game, rendered with my pixel art shader. It's super pretty! All the maps from the previous one will be in the same format, so it will just convert it all to 3D. The main focus of this game is sandbox/multiplayer, I think it's important to be backwards compatible.
I still support C2 for 2D games though, and will probably use Construct for the rest of my friggin' life. Lol