Some important fundamentals...What questions you can answer, what conclusions you can draw, what tools/techniques you use for analysis, interpretation of the results, confidence in your ability to extrapolate conclusions ALL DEPEND ON HOW THE DATA WAS ACQUIRED! While you can certainly "play games" of analysis by changing factors data types, ultimately the analysis should be appropriate for the data type. For example, let's take a continuous factor at 3-levels vs. a categorical factor at 3-levels: it certainly makes sense to estimate a quadratic effect for the continuous variable, but it makes no sense for a categorical factor. That given, since your data is from an experiment, discrete numeric will give you the same model as continuous variables tested at the same specified number of levels.
"All models are wrong, some are useful" G.E.P. Box