MBR1200 user here. Running 1.70
L O V E I T !
Supports just about everything we've thrown at it. Great road warrior tool. We've run 10-12 people on it with Sprint, AT&T, and All-Tel modems. Combine it with OpenDNS and you've got a powerhouse.
As far as updates go, I read what they offer and if nothing earth moving(security/features I'd like to play with) I pass.

As others have noted the need to exceed the 5 device limit is a compiling factor to get a Cradlepoint. Also, it charges the modems/phones(if needed) which is a huge plus on long projects. Plus 4 wired ports is a nice back up.

As for the devices you are using:
Verizon Novatel 2200 MiFi = Plug and Play functionality
Virgin USB broadband unit(guessing the Ovation MC760)? = Plug and Play functionality
tethering my Android with T-Mobile. = Might not work, Android support on Cradlepoint devices is poor/non-existent at the moment.