Hi,
I like where you/Anima are going with the `grinding is useless after point X'. You have my axe. And my credit card number, probably.
Anyway, I just wanted to add my thoughts in grinding. Incorporating grinding (by which I mean `unlimited random encounters with unlimited benefits') IMO raises two concerns:
(a) annoying interruptions in the game flow because the game can't tell whether you're travelling because you want to grind or whether you're travelling because you want to get somewhere. FF solves this with airships, Ultima V/VI/VII solve it with a magic carpet, while many other games, such as QfG, solve it with running. Except for Ultima IV, where running from a fight is not virtuous and hence a bad idea.
(b) you can't tell how much you're supposed to have levelled up to proceed.
You're mostly addressing point (b) here. Please note that if grinding can have significant effect (including providing you with advanced equipment, which seems to be the plan), then there should always be a way to back off from an encounter to grind some more, if otherwise you might have no chance to win (at least if you prefer the LucasArts school of game design over the Sierra On-Line school of game design.) If that doesn't fit the story, one approach may be to disable save games while you're in such a `critical section' of the story.
Meanwhile, addressing concern (a) is also worthwhile-- perhaps you can re-use the hovercraft for that purpose? Note that FF VI had one random encounter on the airship, which was a special boss. That one was fun, because it was a one-time interruption. Multiple of those would be conceivable (e.g., 3 different one-time bosses that intercept the hovercraft, plus location-specific things).
As for Tiled: I'm not sure if you have noticed this, but you can also use Tiled to have multiple layers on top of each other (or at least that used to be possible). For example, you can have a ground layer (desert), then a rubble layer with optional rubble tiles, and then a cactus layer with optional cactus tiles. If you have 4 desert tiles, 4 rubble tiles, and 3 cactus tiles, that's 4*5*4=80 different combinations, leading to higher variation in your maps. (The Mana World (free/Open Source MMORPG with lots and lots and lots of grinding) used this to quite some effect, though most tmw maps were built with the older Java version of Tiled, which may have had a different feature set.)
BTW, since this has been brought up in this thread and not been deemed off-topic: the hardest difficulty level on PS was very appealing-- fights were challenging, which made them fun. Loren was easier in that respect, but then again, I spent a lot of time grinding in Loren. (Incidentally, that was also the point when I stopped playing Loren for a couple of months. In case you wanted another data point on this.
-- peregrin