I've been down Big Fat Gap too. If I'm remembering correctly, and this is true of most trails in these parts, it's the section closest to the ridge that's the steepest. The Little Slickrock trail is no exception, and once it picks up the creek, it's easy going. I've have to say there's practically no difference in difficulty coming out with either of the trails; the last 1/2 mile will kill you on both, but it's short.
Jim: With regard to the Green Drake hatch you mention that was present at least 20 years ago -- was it duns or spinners you fished to?