Well....

The DS remakes really don't use the two screen too much, and they both do not require a stylus. In III, pretty much everything is on one screen. The top screen is only used for maps and such.

IV uses both screens, but very intelligently. The top screen is all your action, while the bottom acts as maps and, when in battle, shows the ATB and HP and such.

I seriously doubt these will ever go to PSP, but I guess anything can happen and you should never say never.

These two games were the only reason I bought my DS (initally), but with other great games like Tetris DS and Front Mission and such, I prefer my DS to my PSP. I really only use my PSP for homebrew. I own 0 PSP games, because none appeal to me, and if they do, they're PSX ports and I either already own them to play on PSX and play on my PSP or I just pirate anyway.