I'll separate financial portion of discussion therefore answer topic 2 first:
2: "Most of the major VMS's have some form of redundancy "
Exactly, and this is a part of premium, top of the line version of these few VMS. But there are no storage platforms offering such embedded capability – you have to get it through VMS.
By the way VMS failover and Pivot3 failover are not exclusive, they are actually work well together providing more even resilient platform.
3.1:"Pivot3 is essentially a virtualization vendor".
Yes & No: Yes - Pivot3 utilizes VMware. No - It is hard to name Pivot as virtualization vendor as Pivot did not create its own virtualization platform. Nowadays virtualization is overly accepted and preferred in IT world, therefore calling system running VM as 'virtualization vendor' maybe viewed as outdated approach.
3.2: "can we also agree that Pivot3's ability to deliver all of these features is moderately dependent on the camera/software platform (eg: Pivot3 cannot deliver all the same things for Mobotix that they can for Axis/Milestone)?"
I would have to disagree here: Failover is available to any system that is running on Pivot3 same as access to data in case of server/hardware failure. Yes, this feature was originally geared towards VMS systems, especially for those ones that lacked it, but it is available for anything now. You can transform your Access Control, Building Management, SCADA, etc server into redundant solution.
4: Thank you for bringing up intersting items to discuss :)