Answering Gunther's question in another post about what caused the elimination of the reversed R, this was the official word, from Leslie and Zoubek's "A List of Changes in the New Gregg Shorthand Manual":
"The most important simplification, however, is the complete omission of the reversing principle. Next in importance are the presentation of a simple, definite rule for the omission of r, and the presentation of a simple, definite rule for the past tense -- a rule with no exceptions.
The relatively limited usefulness of the reversing principle in business dictation does not compensate for the difficulties it causes in the learning of shorthand for use in the business office. The reversing principle may be worth while for the one in a thousand who goes on to become a court reporter. It is definitely a handicap to the ordinary learner intending to become an office stenographer. It introduces an element of doubt into the writing of a large percentage of circle joinings. This doubt hampers the acquisition of shorthand speed because of the hesitation over every circle written on a straight line. The elimination of the reversing principle immediately removes one of the most difficult single parts of the shorthand learning and results in a remarkably rapid development of shorthand speed when dictation is begun.
The dropping of the reversing principle is not only helpful because of the saving of time in the learning of the reversing principle itself but also because it is one of the factors necessary for the working our of a simple and consistent method of representing the past tense.
For at least thirty years teachers have been suggesting that rd be expressed by raising the end of the r just as ld is expressed by raising the end of the l. The adoption of this suggestion in the new Manual means that a large proportion of the words formerly written with the reversing principle or by the omission of the r can now be written in full with the rd.
Many of the reversing principle words reversed the circle before n, m, sh, ch, j. The joinings of r before these letters present no new problem as the learner becomes accustomed to them early in the study of shorthand. The only new joining is rt, which is the same joining that has always been used for "melt", "salt", etc."