Agilent SureSelect XT Capture vs. SureSelect XT2 Capture? Pre/post capture indexing?

[DMH010]

With my current understanding, with XT2, you pool all of the samples together and then use the capture. While with XT, you use the capture individually on each sample.

I'm trying to understand in which instances would you want to capture before you index and which you would want to capture after indexing?

What are the pro's and con's and which applications are they specific to??