Where's the HR in this?
Vyvanse (lisdexamfetamine/L-lysine-dextro-amphetamine) is a prodrug for dextroamphetamine. Dexedrine is just that, dextroamphetamine. They're almost interchangeable. Vyvanse gave me all sorts of stomach issues and lasted a longer time than I would have liked (although I can see its usefulness when it comes to studying/schoolwork/ADHD treatment) but I would just go with Dexedrine Spansule (Dexedrine XR/SR) if I needed long-release dexamphetamine.
Long story short, find the one that works best for you.