Do a google for "seat mystery blue" and you'll see a loads of them. Looks good to me. I always prefer blue though. Currently in Alor blue, but I'd definitely go for mystery blue over red.
Alor blue is the best blue Seat did, shame they removed it from an option. Mystery has to be second best blue to go for !
One consideration - the 'R' in 'FR' is red - do you want it to pop out (ie stand out against the Mystery Blue) or be colour-coordinated with the Desire Red?
I didn't actually go this far with my Leon, but when I was considering a Polo GTi I was avoiding the red because I wanted the red stripe on the front grille to stand out.
Yeah I'd definitely go for mystery blue. Though I'm curious what Speed metallic blue looks like.
Cheers,
Try Googling ‘Speed Blue Seat Leon’ - there’s lots of pictures. It was a colour available on the mk2 Leon.