I find this kind of interesting. I'm pretty sure that HD-SDI can run through cheap coax / BNC Connectors / especially for short distances. In other words, you can use SD cables for HD-SDI in short-run applications.
I'm wondering if you could tap into the stock 9 pin / hack the end off and put a BNC connector on it and run a HD SDI signal to a HD-SDI monitor.
I'm looking into getting mine upgraded to run a Scarlet and I've been in touch with Terry. Buying a new HD-SDI monitor and rewiring the thing isn't cheap - but I think it will be worth it.
Best,
Wes