Got FF I PR beaten in two days. My team was the canon one: WAR, THF, WHM, BLM It was quite slow at the beginning, but after Astos it got really smooth, with Auto-Battle. I broke the sequence quite a bit, though. I decided to get the airship before Mount Gulug, so I got quite overpowered for the rest of the game. The only hard battle at that point was against the Warmech. Also, using the magic from the weapons and accessories was a life-changer, especially when fighting bosses. Haste and Temper made wonders against Chaos. After finishing it, I almost got crazy in the 15 Puzzle but at least the achievements are done.
I didn't mind that the sprite work was LCD-centric and (yeah) inspired by Record Keeper and the FF Dot book. It looks nicer when using Reshade and the converted CRT shaders from Libretro, in my case easymode and Geom did the good work. Oh, and the arranged soundtrack is really great, I could expect a complete soundtrack release of all the 6 games.
So yeah, it is plausible to beat the at ~10 hours, even more if you want the rare enemies. Now I am not sure if getting FF II first (although it is quite broken judging from the comments in this thread) or jumping directly to III.