If you're going that way, then Yoshi P must hate FFX since we only got Yojimbo and a few music notes in Stormblood that reminds me of it (althought I might have forgotten some things).

I agree with everyone else ; I actually feel like there are a lot of FFIX plot elements, callbacks and nods here and there. I was impressed with Solution Nine having a tons of little winks to the monsters, the trial was great, the music in both the dungeon and the trial were awesome.
Speaking of music, you got a tons of remixes from FFIX ; the Court Jesters is remixed for The Strayborough Deadwalk dungeon, the Tantalus' Theme is slow remixed for the hud in Solution Nine...

I actually believe they did a great job regarding FFIX.