I think each Lunar let you save wherever, so worrying about battery life shouldn't be a big issue unless you're caught in long-ish cutscenes or battles. And of all the genres where you move around a character RPGs are probably one of the only ones that CAN work on a phone or touch screen. Your reflexes don't matter except maybe to avoid enemies, which isn't going to be an issue if this is the Sega CD version and I recall they were kind of a pain to avoid anyway in the 32-bit version. You want games that are more troublesome to properly convert to phones, look at platformers or FPSes, though even those have been done respectably enough (well, not for me) on the iPhone.
By the way, I'd generally prefer not playing RPGs on a phone or iPod touch anyway. Especially not a phone; I'm not worried about saving in time, I'd be worried about having enough battery life for phone calls.
