...you don't have to have a laptop with you to drive the device....
... this is the essential point to bear in mind when comparing the Datrend approach with others (especially Ansur). It's a practical (real world) consideration.
In short, vPad (Datrend) uses Android tablets to "drive the device" (test equipment), with "apps" to be installed depending upon which test equipment in being used (and which, if any, CMMS is to be linked to). In fact, you could say that the tablet is part of the test equipment (a situation that becomes obvious when you glance at the latest Datrend test equipment).
Whereas Ansur needs (uses) a "plug-in" (dedicated software) for each item of test equipment (electrical safety tester, NIBP tester
etc.), vPad uses an "app".
I believe there is merit in both approaches. For instance, I like the "drag and drop" style of the Ansur template building "screen" - it's (what they call) "intuitive" (and has been that way from the very first Metron versions).
From the little I've seen so far of OneQA, it seems to be very PC - or large laptop - centric, and what we might call "document based".
CMMS integration is difficult, but not impossible. It depends if you really think you need it ...
Yes; wise words.