i got both redring and FTD, so i do this:
RR = for general use and "common" bosses
FTD = for high lvl maps with massive number of monsters, use against megid and grantz, use against Ultimate bosses [Fallz,Flow and Kondrieu only]
BUT STILL: i preffer FTD for its style and because it is a unique item, only the ones that used to farm the DF shield at the old days when it was dropping at normal black paper deal² was able to do that shield.