RGEM is not a questionable model. It's the high resolution version of the CMC. Here's an excerpt from weathermodels.com on the RGEM:
How is the RGEM’s forecast data best used? The RGEM is a regional model, so its strength is depicting smaller scale features that the global models may miss. The model is especially good at figuring out the overall structure of storms, and often does pretty well with heavy snow bands. Of course, no model is perfect, but generally this one is pretty good.