DX9 and DX9EX cause texture bugs, invisible enemies, and spoil abyss cracks

At least on my system (with a Radeon HD 3670 GFX card) DX9 and EX produce some strange texture layering bugs that cover up enemies, rendering them invisible. So far I've confirmed this in some areas with pathable water (e.g. Mud Flats in A1, The Wetlands in A2). In addition, the cracks for abysses show on top of the terrain, similarly hiding monsters behind them and spoiling where the next leg of the abyss will run. I would very much like to see this fixed, since I find DX11 hobbled by some serious performance issues.
This may or may not be related to my previous (and still relevant) report about breaches being mostly invisible.

P.S. I neglected to get a /bug in the Flats screenshots but none of this is instance specific; I see this behavior in all Mud Flats and all abyss cracks.

I responded in your other thread regarding DX11; executive summary is "sounds like hardware or driver problems, which sucks"