Hey edm,
I bought the Annihilator 2 MX... "BIG mistake!", I thought at first... I totally overlooked that the data-path between video-RAM and the gfx-chip is 64bit

So if you have enough money, go get the GTS!
Performance is not bad with the Annihilator2MX but it's not as fast as a SDR-version with 128bit data-path. And don't forget: it comes without a heatsink.
So the next thing I'm going to do, is attach a heatsink and o/c it to 200. the video-RAM is working at 143MHz (that is 286 DDR) by default. I checked 166MHz (333DDR) and it worked flawlessly (10x loop in 3dmark2k). (Hyundai 7ns)
Here are my 3dmark results (at default clock 175/286):
4110 3D marks
388 CPU 3D marks
79,9 FPS
59,3 FPS
27,8 FPS
83,6 FPS
56,6 FPS
35,1 FPS
297,3 MTexels/s
577 MTexels/s
6707 KTriangles/s
4887 KTriangles/s
2866 KTriangles/s
192,9 FPS
185,3 FPS
141,3 FPS
75,5 FPS
110,2 FPS
133,4 FPS
196,6 FPS
Not supported FPS
o/c'ed 175/334:
4431 3D marks
404 CPU 3D marks
86,3 FPS
64,1 FPS
31,4 FPS
93,9 FPS
58,2 FPS
35,4 FPS
318,8 MTexels/s
624,1 MTexels/s
7206 KTriangles/s
5104 KTriangles/s
2924 KTriangles/s
219,5 FPS
209,2 FPS
147,2 FPS
75,4 FPS
129,2 FPS
156,5 FPS
225,2 FPS
Not supported FPS
my specs:
p3-650E
160MB-RAM
W98SE/DX8/Det 6.34