Can a USB Oscilloscope be used reliably and accurately for RF projects?
What does one thing have to do with another?  You look at a big expensive scope it is a windows computer with some boards in it for the measurement interfaces as well as the knobs and buttons.  This day and age do we really need that?  Knobs and buttons are superior to touch screens yes, but there is no technical reason why they cant build the same quality scope as far as measurement capability goes.  Being wrapped by a computer display and knobs does not affect the quality of the  measurement for a properly designed scope.  No reason other than profit selling is a computer and buttons at an inflated price, that they cant provide high speed high quality scopes that we connect to via ethernet or usb and run software on a computer we provide. 

Being a non-screen, non-button scope does not have anything to do with the potential quality of the measurement.  Nor does having buttons and a screen make a scopes ability to measure and display a signal any better.  A bad scope is bad scope in whatever form factor.  As is a good one.

If your real question is, are these specific products I named any good, I would say that falls under recommending a product and the question should be closed.