My former employer, TWA, made extensive use of this during our post bankruptcy cost control efforts. We had quite a lot of data, which, sadly, they did not think to send me prior to the merger with AA.
Seriously, it was standard practice even for short taxi. Our procedures were well designed and very well practiced.
In terms of fuel savings, it matters quite little for a small fleet. However, when considering a large fleet, our belief was that the small percentage of fuel saved over one year by each of several hundred daily operations could be significant.
The only safety issue that I have ever been aware of with this practice is the use of excess thrust in the ramp area. This can, of course, be very serious if you happen to be at the receiving end of the debris field. But it is easily controlled with weight limits, N1 limits and a smattering of good judgement.
Boeing, naturally, discourages this practice, but I really don't think there is any basis for this other than not-invented-here syndrome.