Bart,
That works great for aircraft but range checking a multirotor just doesn't provide the visual stimulus of moving flight surfaces. This is an area where someone with the imagination and skills could develop a new product that would provide such stimulus for range checks. Link it to a multirotor and the transmitter.
As Fltundra noted, and analyzer is great for checking a noise floor but for checking the specific frequencies things could be kind of tough. Most of the 2/4 systems now employ a hop table and I doubt many know what that table and series of frequencies is. Wireless routers broadcast WiFi on 2.4 and 5.8 and combined with all the other consumer products using these bands we would expect an analyzer to indicate things are pretty busy.
