Can't speak for Gulfstreams, but Challenger 300s and Globals are Cat C for all approaches, straightin and circling. They both circle with landing flaps set.
The Honeywell FMS DB for the GLEX (Classic and XRS) did have several special RNP approaches available for selection. However, they required FAA authorization and I understand they should not have been included in the data set. In any case, flown visually, they had a normal vertical path, in the area of 3 degrees and wound quite nicely around the plateau on the approach. The valley rises such that, visual maneuvering can be flown with a reasonable descent rate.