So here how it looks when it's flying. The sparkling particles have ice/crystal sound.

Regarding the running. Fenrir seems to be smoother than Coeurl but it could just be me. They both have same mount music (but you can disable mount music if you don't like it).

I persoannly think that Fenrir is definitely worth getting. 1 mil MGP doesn't take that long. I did Triple Triad Tournament, GATEs and daily cactpot and got 1 mil and that was before they added challenges, so with challenges it will be even faster.