If it were my kid....the 2lt would be the choice. Less power, better mpg, lower Insurance. Although for my kid, i'd buy a cheap, used "beater" for him first till he learns how to drive. I think new drivers should earn a nice car, learn to respect the responsibility first before they get dropped in a new muscle car. Just my .02, it's your son.
2010 R6P-2SS/RS/LS3 - IBM w/ silver rally stripes