No, nothing except resources is in the way of completion of a move to a more modern platform. It's coming gradually, but we can't drop everything for a year or two to devote all of our engineering resources to getting us there.

OpenVMS has some really good ideas baked into the OS that we've had to reimplement or find off-the-shelf solutions for our new platform (for example a distributed key-value store (called "logicals"), a job queue system, and a clustered filesystem) but nothing so earth-shattering that it would keep us on VMS.

The biggest downsides are expensive hardware (OpenVMS is designed around clusters of a few beefy boxes, rather than many commodity boxes), lack of community knowledge, and lack of new software available for the platform. (End of life is also looming: http://h71000.www7.hp.com/openvms/openvms_supportchart.html .)