I don't have a large sampling statistic to go by either, but I have heard several professionals that are heavily bought in to the Mac Pro ecosystem complaining about the state of the Mac Pro and either have started building hackintoshes or were seriously considering it but holding off....
I've heard similar, save the willingness to go with a hackintosh.
Those that indicated they would take this route, tended to be very short on physical cash (i.e. little to no choice, based on funds). Most indicated they would have to switch to Windows however, as Linux wasn't really plausible for their needs.
These are the people that NEED the Thunderbolt and/or USB 3 connectivity in their workflow and the raw horsepower of the Mac Pro running at 100% CPU across all threads. You can currently get both Thunderbolt and USB 3 in hack-pro but not a mac pro.
I don't see it this way, based on what clients I've dealt with are primarily doing.
Yes, some could benefit due to sharing devices between field work and their workstations (i.e. location shooting using a camera, laptop, and portable disks, and editing that content back at the office on their MP's). But this is currently a small % from what I'm seeing (those that get their own location data).
But overall, it's more interest in a new product than actual need from what I've seen and discussed.
My reasoning, is that most apparently get that content sent to them from the client, and connect to it on a more common interface, such as eSATA or FW800.
Obviously this could change, but that will take time (needs further market saturation/increased adoption levels), assuming this isn't displaced by by other technology, such as 100Mb/s or better ISP plans in pretty much any location (same cost or less than what they may be paying for 1.5Mb/s or so for example; figuring on a 10x fold increase in throughput with little to no cost increase).