Duane, GMaps does allow you to save a course and the elevation profile, and send the link to a client. However, it does not provide an editing capacity. Few clients I work with have the ability to use either MapMyRun or GMaps, it seems.
The last time I tried MapMyRun, many months ago, I did not see an option to draw a manual route. So, if a route traverses a paved path that does not show up on the map or parking lot, I was not able to complete the route on MMR, while GMaps does a fine job.
I do have one client who recently sent me MMRs of 2 courses he hired me to measure. In both instances, my GMap of the same route produced a distinctly longer 5K course. This resulted in a significantly different start and finish in each instance. The courses as measured turned out to be almost exactly what GMaps showed them to be - which was quite different than the MMR editions. I can send you or post the links if you or anyone is interested so you can see the differences.
BTW, you have an excellent Web site.