Both A and X have what appears to be fairly similar PCIe cores for the S4 
and V6 respectively. The A version uses streaming Avalon, the X version 
streaming AXI. I need 8X PCIe 2, with DMA support, I'm agnostic about A vs 
X, I'm comfortable with both.

Has anyone done a comparison between the two, what are the key differences?

I'd like to know what experiences people have had with these cores, what 
problems if any? 

Also do they provide Linux drivers? If so how complete are they?

Did anyone see this video of 13.1?
https://xilinx.webex.com/xilinx/lsr.php?AT=pb&SP=EC&rID=3372608&rKey=38aaf4d8e5851be5

Looks like a big leap forward...