A 360deg circular move can't be programmed in one Block using R Format. In every case where I've seen a full circle programmed using R Format, the user has programmed two Command Blocks, each dealing with 180degs of the full circle; logical on the surface, but not so. Being able to programming the circle in one Block is the first plus for IJK Format in my book.
If there is an error, caused by rounding, minuscule as it may be, when the Control calculates the centre of the arc and shifts the arc centre, there will be a doubling of the error as the shift of the centres will be in opposite directions in each of the 180deg arcs, but it seems that theoretical accuracy matters little to you.