Heat treat will make the most out of your knives. You can pound out steel all day long, and you can do a successful heat treat in the forge. But in my opinion, you cannot match the consistency from a digital oven, allowing you to faithfully perform optimum heat treats to each and every knife you build. I know many amazing makers who heat treat only in the forge, and I would buy their knives in a heartbeat, but I know if it was me, I wouldn't trust myself to get it right in the forge every time.
Plus, you can build a forge for a whole pile less than an Evenheat.
--nathan