[c-nsp] To XR or not to XR

[Mark Wheadon]

What has been people's experience of Cisco IOS XR on the 12000 series ? 
TAC have advised that12.0(33)S has been frozen in development and only 
bug fixes or security fixes will be made to the code base.

I have read that XR can take substantially longer to boot compared to 
IOS on the same hardware. XR 4 is mean't to improve the boot time.
Flash Memory requirements have grown from 512meg of ram to 2G on the 
latest release of software (3.9).
TAC give the impression that XR on 12000 series hasn't been widely adopted.