Question re DX10 and photo scenery?

Since there have been recent changes by Dovetail in the way FSX:SE handles scenery loading / unloading and given that DX10 passes textures more to the GPU, assuming one is running Steve's DX10 Fixer is it better to run in DX10 mode with photo scenery such as Horizons GenX, or stick to DX9 when using FSX: SE ?

Does anyone recommend best settings in either DX10 or DX9, when using FSX Steam, to best help loading photo textures to maintain sharpest texture tiles given a low end system? I currently have autogen turned off to maximise resources for texture loading.

My lowly system specs are:

AMD PhenomII quad core 2.6 CPU

XFX GforceGTX 260 2gbyte graphic card

8 Gbyte RAM

2x 7200 rpm HD drives

Cheers,

Stuart