Xen users - Oct 2014 - Consequences of disabling interrupt remapping?

Hi all,

I have a box I'd like to use with Xen, and I'm hoping to use VGA and PCI
passthrough. However, the machine suffers from this errata:

https://support.citrix.com/article/CTX136517

So it looks like I need to disable interrupt remapping. What are the 
practical downsides of doing this? Will it prevent me from using 
passthrough?

Thanks,

Steve