I don't know if I'd start the lad out on GYBE.
In fact, i disagree w/ that being a good starting list.
It was more of a "personal preferences" of relatively obscure
prog bands than "progressive rock 101".
IMO-Stick to the basics- Yes, KC, Tull, Gabriel/Genesis, Floyd, Rush.
These are the bands that started a great percentage of us.
After a good grounding, move into Gentle Giant, Porcupine Tree,
early Spock's Beard. At 17 ( possessing a surplus of testoterone
and adrenalin that most of us here lack), you'll probably like Dream Theater.
Also, give a listen to the Mexican prog band "Cast".
Thase had a pretty good CD a couple of years ago, "Nimbus".
Unlike Magma, ect., Most of these can also be found on YouTube.com,
a better way of checking them out w/o shelling out
el grande pesos.
BTW- Are you familiar w/ the Mexican band "Mana"?
I know/jammed w/ their little brother Abraham.
Great drummer. He left the band, thinking he was better than
his brothers,
6 months before they were signed to Columbia Records 
P e a c e and welcome to the moon,
Kirk/Zenpool