Actually you need both. You do need to grind some times because rushing through the game doesn't net enough exp ( I am using custom stat growth, hp / mp growth and exp curves. you need roughly 4x as much exp for lvl 99 as before, but you get much more hp/mp, while your base stats never really go beyond 100. ) to survive the bosses.
for example, I am lvl 20 at bottomswell, and he rapes me pretty hard unless I notoriously exploit his weakness ( bolt, slow, limit attacks with bolt element attached to weapon, etc ) and it's STILL hard then.
At some point, you ARE maxed out. you have all the strongest materia and maximum level. And at that point, you will still have non-optional bosses before you that will hurt you like crap.
Also, I said it's hardcore for a hardcore gamer. I guess that makes it some kind of over-the-top nonsense difficulty for a normal person. The kind of difficulty the original battletoads SNES game had. ( which was so difficult that it was near impossible to win even WITH INFINITE LIVES )
For example, Emerald Weapon has a lot more than just damage in it's repoirtare now. The eyes all cause several negative status effects, air tam storm is no longer fixed by materia but a 'shout' element attack that pierces def, status barriers and dispels you. Emerald Beam is reflectable now, but if you DO reflect it, it *heals* emerald weapon back to full health. Also, it cuts the damage of KotR in half by resistance. Not to mention all the other crazy stuff.
Even with maximum stats and best equip, this guy is one hell of a challange.
I would release a patch for my version but I can't because of several reasons.
a) it is based on gjo's hardcore mod and includes his custom encounters ( all beefed up though )
b) I don't even know what changes I made where, so I would have to ship the entire scene.bin and flevel.bin
c) I dont think plagiarism is likely to make a good impression here.
I better stop going off-topic here before obesebear has a field day with me.