Analyze the feasibility of investing $5,000,000 of capital gains into a Qualified Opportunity Zone (QOZ) fund focused on mixed-use commercial development. Compare the tax deferral benefits, step-up in basis, and tax exemption on gains held for 10 years against a standard 1031 exchange into a like-kind property. In your analysis, calculate the projected tax savings assuming the original capital gain was generated from a high-frequency stock trade held for 6 months. Discuss the specific risks associated with QOZ investments, such as liquidity constraints, regulatory changes, and execution risk regarding the 'substantial improvement' requirement.