Permadeath can be super frustrating. Battles can take a loooong time,
and restarting one sucks a lot. It really changes the way you play: you have to be cautious about everything. Some people really like it; I personally hated it. Barely made it through FE7, despite loving other SRPGs (FFT, Disgaea, etc.).
I'm planning to try Hard Casual. Don't know how it'll compare to Normal Classic, but I reckon Normal Casual would be way too easy. The game is balanced around Classic, so you're expected to be able to beat every mission without losing anyone.
But at the same time, if you go Normal Casual, it's easier to handicap yourself later if it's too easy (eg, only use (N-1) characters on maps, or use all the characters instead of leveling a core team, etc.). If halfway through you find the game too hard, you've either gotta grind or restart
It's a tough call, no doubt.