Of course, I run native mostly. But sometimes I like the simplicity of running non-native. And sometimes I use effects. Of course none are perfect. The effects rendering before the re-write (generally 50% scanlines) was perfect in gradation but affected the color/brightness output. The new rendering isn't as good, but has far less effect on the output.
Lately, I've found out the 'scanrez2' is pretty decent. Some games it works better on, for example DKJr is almost perfect, but Pac games aren't, so since they're PNGs I'm guessing it's a matter of pixel rendering vs the what resolution and all the overlay image created in.
This is on my 27" monitor, though. Trying to get the same kind of look as when I run native on it, which is also the same as the effect given by the old rendering system, none of the effects work for me on a PC monitor...so maybe this is a lame post.