I was at Fremont Peak on the night of August 16-17 with my Intes 6-inch Maksutov; I split eta CrB [Coronae Borealis] fairly easily at 375x, but got no trace of elongation on gamma CrB at the same magnification. Later in the evening, I got a nice elongation of gamma-two Andromeda at 600x, though. The telescope was working well on deep-sky objects, too -- at 47x I had a nice view of the Merope nebula after the Pleiades had risen, and was able to see two dark lanes in M31, as well as the star cloud (NGC 206) that is part way out in the galaxy, on the same side of the nucleus as M32. M31 appeared well over five degrees wide.
It's interesting actually to have a use for 100x per inch of aperture. To look for an elongation, and a rather small one, in the central part of an Airy disc is to look for details in the image at an angular scale substantially below Dawes's limit; hence very high magnifications may be required.