Kind of an old thread but I just love to rep etrian odyssey's awesomeness. You sound a lot like me as far as game preferences and skill goes. I also heard Devil Survivor was hard but I raped the Bels only having somewhat of a problem with Beldr (cause of my magic nuke with 4 or 5 st
). Anyways I have played Etrian Odyssey 1 and 3 and the third one is definitely worth playing! Sure it's difficult in some places, but only because it requires strategy. If you were able to beat Nocturne and Devil Survivor with ease I'm sure you will enjoy the difficulty in EO3, as I found it slightly harder than the 2.
The mapping in the game also put me off for a while, but you will find that it actually compliments to the exploration aspects of the game very well and it is quite useful to make notes of places you need to return to later. It auto maps the ground you cover which makes it much less tedious than one would expect. EO3 is worth your time and money IMO!