I'm not on Advantage but what I could tell it just gives the exact same s/w no more than 2-3 days before it's widely available anyway. Locking in pricing is questionable as to your point there are many discounts below Intuit's pricing whether it's Amazon etc or brokerage offers.
But I suppose it does provide other benefits...
https://turbotax.intuit.com/personal-taxes/cd-download/advantage/?_gl=1*vxv2p7*_gcl_au*NTgwMjMzODAxL...
