Two different low energy proton (LEP) test methods, one with quasi-monoenergetic and the other with very wide proton beam energy spectra, have been studied. The two test methodologies have been applied to devices that were suggested from prior heavy-ion tests to be sensitive to proton direct ionization (PDI). The advantages and disadvantages of the two test methods are discussed. The test method using quasi-monoenergetic beams requires device preparation and high energy resolution beams, but delivers results that can be interpreted directly and can be used in various soft error rate (SER) calculation methods. The other method, using a heavily degraded high energy proton beam, requires little to no device preparation but more efforts on the beam characterization, and is confined to a specific SER method. While both methods deliver comparable estimates on the SER, the relatively complex determination of the beam characteristics in the degraded beam method makes it less straightforward to use. This work furthers presents a method to extract PDI sensitive volume parameters from degraded high energy proton beam cross-section data. This method extends the use of a previously published method to the degraded high energy beam LEP testing method.