With Diablo's Encounter-None skill, you'd only ever have to fight boss type monsters, right? Therefore they'd be the only way of getting Exp points and leveling up...

Because the monsters level are directly related to your own, I thought I'd try it out - I had to get my characters up to level 7 before I was able to give Diablo enough AP to learn Enc-None but it made the next few stages of the game much easier.

When I get my FFVIII game back (I'd left it at my mum's place) I'm going to try completeing the game keeping my level as low as possible, to see how easy it is.