I've beaten FE6 HM for the first time and I've to admit it was hard even frustating in some points.
Not mainly because of the difficulty, but because of the game mechanics. Physical range weapons are crap an the weird RNG pissed me off. I haven't count, how many times my units missed with 70% but the enemies hit me with 30%.
The earlygame was pretty tough, especially chapter 6 and 7. Chapter 7 was as a nightmare as I expected. However the game became easier, if my team got some levels.
Rutger saved my ass against most bosses.
The stats of the enemies seemed to be fair to me. The stats of the phyisical enemies weren't very special except for high HP.
Myrmidons maxed skill and speed, mercenaries maxed skill and dracoknights maxed strength. Maybe comparable with FE10 hard mode.
Second tier enemies weren't too tough.
Noticeable was the high magic of enemy sages and druids. Level 10 druids had maxed magic already, which was very annoying because of the huge range of their staves.
Most of my staves like silence, sleep and berserk didn't work against the enemies because of the ridiculous low magic stats of Ellen and Clarine. Bolting was my remedy to kill the enemy berserk users.
All in all the difficulty was alright except for chapter 7 and the desert chapter.
If the accuracy of axes and lances was better, this game would be more bearable for me.
I'll switch to the "Redux Hack", because axes and lances are improved and some chapters and character growthrates are fixed.