Mike,
Thanks for the reply. Sorry for the confusion on my question but I didn't mean to say or imply that there would be any desire to mix map and feature service symbology. I meant to only refer to feature services, so I updated my question. Does that change your answer at all? Also, I don't have any desire to have any fancy symbols, basically some symbol ones that show either a single letter or number. There is already a few that show letters available in the ArcGIS viewer but none with simple numbers. Seems like this is a pretty common request, I see several separate requests but very much related ones on the ideas site.