As far as memory goes, the VRayBmpFilter texture behaves exactly like a standard 3ds max bitmap texture.
VRayBmpFilter does not apply any texture filtering, other than a simple interpolation between the bitmap pixels; normally, for textures that are far away from the camera it is useful to have some filtering so as to avoid noise in animations and to make the job of the image sampler easier.
Of course, nothing stops you from using VRayBmpFilter for other textures in the scene - in fact, this is more precise than using texture filtering (which is basically a cheat, even though a successful one in many cases).