I see where you are coming from here, but the problem is that the lack of effects cause some things to happen. You can't really discern flow or depth with just a couple of a effects. Which causes it to look like you kinda pasted the render into the BG, I think they used to call it blending. I mean the rules may have changed since I GFXed seriously but it doesn't look very organic.
I know you have done more than just pasted it into a BG but without the effects blending the foreground and the background it looks like a copy and paste job. I mean, maybe it is just me, this is just my opinion and if you are happy with it then my opinion doesn't matter. This was just what I saw from my prospective.