Anisotropic Options with 9700

Funny things tend to happen when calculating LOD. I wouldn't be too concerned about that. Although it isn't clear the last anisotropic shot is curved at all.

TNTx cards did it like that, but I think Radeon 7500/8500 cards are more depth based (as opposed to the range-like 9700 or any Geforce). Most of the time the boundaries on a Radeon 7500/8500 look straight horizontally. TNTx cards had the two colliding boundaries as you describe.
FYI, I know at least the first gen Geforce cards weren't using perfectly curved surfaces, they just used the junction of something like 5 lines. I haven't tested my GF3, yet.