I just noticed the posts about the comma in Gregg. One suggestion I've seen, and that I've adopted, is to use a double Gregg period for a comma (that is, two short backhand strokes close together). It's easy to read and takes less time and effort than a comma in a circle.
I believe the comma in a circle was first used in the Simplified manuals to show where a comma should be transcribed, and the circle was to differentiate it from the letter s. Secretaries could easily use this notation in dictation, provided the dictator said "comma" when he/she wanted one. But in other rapid writing where a comma might be useful, this notation is burdensome and slow.