For anyone doing a search on this in the future, I can report success with my Novatel U727 USB gizmo - configured with SPRINT - though I had to select "Verizon" as the configuration type.
I also believe I ended up selecting some profoundly low connection rate, like 19200 - It "seemed to work better" like this, but given the flakiness of 3G, I'd have to prod that a lot more to have any sort of certainty.
What's interesting about this 3G interface is that on Windows and Linux, it appears as a CD-Rom drive (containing a "CD" with windows drivers) when first inserted, with a USB ID of (something-I-forget) - after you "eject" the CD drive, the device re-presents itself, with a new USB ID. With linux-based workstations or router platforms, I've had to "manually" (or script-wise) eject the "CD" before setting up the "airprime" module or connecting.
FreeBSD or pfSense appears to be doing the magic for us - which is quite awesome.
(If anyone has tests they'd like me to perform with this device, let me know!)