FYI, here is what the SDK has to say about Fresnel Ramps:
"Fresnel Ramps and Cubic Environment Maps
When assigned and engaged in a material, the Fresnel Ramp defines incident-angle opacity and colorization for a given channel on an object. The reflection characteristics of a material will be affected by any Fresnel Ramp assigned to that channel in the material. As a general rule, any Fresnel Ramp assigned to a channel on a material will mitigate that channel’s opacity. Channels (Reflection, Specular and Diffuse) will almost always appear stronger and more opaque if a Fresnel Ramp is not present as an adjunct to that channel. Unmitigated channels can appear overly forceful, so it is not recommended for most applications that Fresnel Ramps be removed altogether. If a user wishes to reduce the effect of a Fresnel Ramp on most materials it is recommend that they edit it rather than attempt to remove or disable it.
However, for some very specific materials, it is useful to remove the Fresnel Ramps from certain channels (the Glass and Chrome materials used for aircraft, for example). Fresnel Ramps generally reduce the effect of a channel which they are assigned to, but if you are looking to maximize the reflective qualities of such materials as glass and chrome, then remove the Fresnel Ramps. For most materials, those that are not highly reflective, this is not recommended.
As cubic environment maps are what is displayed as the reflections on an object and reflection channels are affected by Fresnel Ramps, developers should remain aware of them and their effect."