Start with the cost side, because the $17k isn't the number you keep.
A license lives under a broker. Even a flat-fee or 100% commission brokerage takes something, often a monthly desk fee plus a per-transaction fee, and that's before local board dues, MLS access, E&O insurance (errors and omissions, the professional liability cover most brokerages require), lockbox access and continuing education. Depending on your market that stack can run $2,000 to $5,000 a year for two closings. You'd also be paying for photography, staging and whatever marketing your old agent absorbed inside her fee, which on a $340k retail flip is not nothing.
So call it $11k to $13k of actual retained cash on two deals. Real money. The question is what you give up.
On disclosure: in most states a licensee selling their own property has to disclose their license status, and the specifics of when and how differ by state, so check your state's rules directly. Practically, it changes buyer-agent behavior more than buyer behavior. Some buyer agents get careful about an unrepresented-on-paper counterparty who is actually a licensee.
Your real risk is the thing you flagged and then dismissed. Two offers over ask on a house you'd already priced at the top is exactly where listing skill shows up, and it's the part that doesn't transfer from knowing how to build. Pricing at the edge of a comp set, holding a position through a lowball, and knowing which of two similar offers will actually close are learned by doing volume. You'd be doing two a year.
There's also a time cost you haven't priced. Showings and offer management land in the middle of your build schedule on the next project.