Even Hector Hard Mode from FE7 is more difficult than the maniac modes for FE9/10. FE6 Hard Mode is harder than Hector Hard Mode though. However, Thracia 776 takes the cake in terms of sadism. Unlike other games, leveling up your characters will not make them be able to breeze through the endgame (hordes of dark mages with permanent staff ailments). There is also the fatigue system in FE5 in addition to the fact that you primarily are only able to get much of your equipment through capturing.
Also fyi, I own cartridges of FE3, FE4, FE5, and FE6. I don't download ROMS, outside of an official service (ie. Wii Virtual Console).