Shinra mansion in Nibelheim is the only area (yet) I had some difficulty with classic mobs. Dorky faces spams too much negative magics. Ghirofelgo is fine. I didn't force fights so I haven't seen any Jersey. Lost number only had one stage unlike in 1.35 which made him easier. Black bats are fine, Ying/Yang deals a lot of damage.
I didn't have much problems with normal encounters anywhere else (I'm currently at the Temple). Even the dragon in Mt. Nibel was fine (not too easy, not impossible. In 1.35 I couldn't beat it the first time I encountered one).
Globally I think normal encounters should have a 20-30% damage boost to match with the new HP/MP curves, maybe slightly less depending on zones.
Edit; I'll mention I run an all-rounder team with Cloud / Yuffie / Red XIII, not using any summon materia, not using any duplicate materia (only one cure, ..) except for "All" materia. These characters have a low VIT/SPR but "high" STR/MAG/DEX and I didn't overlevel since I'm running straight through the game. When I recruited Cid, I replaced Red XIII, Cid being 2 ranks lower I still have no problem with normal encounters. (Having him STR/LCK/SPR)
Edit: It reminds me that at the beginning, Yuffie level 1 limit (Greased Lightning) had a way better damage output that Red XIII (Sled Fang) / Cloud (Cross slash) limits while she had less STR. If I remember correctly she had a 800 damage output while Red & Cloud were around 600.