I'd stay away from buying a 5lb tub until you see you how you react to dextrose post-workout.
I know for me, I have tried Waxy, dextrose, maltodextrin and vitargo, and I have to avoid dextrose and malto because of how bloated I get/feel.
Competing natural, I like to have my post-wo shake w/ carbs followed by another meal within 60 minutes and if I consume dextrose or malto, I'm not eating for at least 2 hrs.
That said, some people can totally tolerate that stuff and it is less expensive. Surge Recovery uses malto and d-glucose in it. I loved the taste, hated the bloat.