Your framing of the exemption as a multiplier on appreciation is arithmetically correct, and it's the reason fund selection dominates the tax analysis in this strategy. On a flat exit the ten-year benefit is worth nothing, and you've still paid management fees for a decade and given up liquidity you'd have had elsewhere.
What can be tested on a blind pool is narrower than most investors think. You can test the sponsor's realized track record in the same asset class and the same construction market, including deals that didn't work. You can test the fee stack against deployed capital rather than committed capital, because a 2% fee charged on commitments during a two-year deployment period is a materially different drag. You can test the governance terms in the operating agreement, specifically what triggers a forced sale before year ten, since an early sale is the one event that destroys the entire tax case for a passive holder.
The One Big Beautiful Bill Act added reporting requirements on qualified opportunity funds, and those obligations sit with the fund. Ask how the sponsor is staffing that, because a manager who has not budgeted for it is telling you something about their back office. Ask also whether their tract exposure survives the tightened eligibility rules taking effect with the new designations on January 1, 2027, and get the answer in writing from their counsel rather than their investor relations person.
The risk you haven't raised is fund-level concentration in a high-cost construction environment. A single ground-up project inside a QOF with a fixed budget and no contingency reload means a cost overrun gets funded by a capital call or by dilution, and a passive investor who can't meet the call is the one who eats it. Check the default provisions before the yield page.