Decompose the returns before you evaluate the people. For each of the six, get entry price, entry NOI, exit price, exit NOI, hold period, and the debt. Then split the gain into the part that came from NOI growth and the part that came from the exit cap being lower than the entry cap. A sponsor who grew NOI 30 percent over three years did something. A sponsor whose NOI grew 6 percent while the cap moved 100 basis points was a passenger. That single table tells you more than any reference call.
Then compare each deal's actual operating results against its original underwriting. Ask for the original pro forma next to the trailing twelve month statements at exit. You're looking at renovation cost per door versus budget, achieved rent premium versus assumed premium, and how long lease-up took. Consistent misses on renovation timing with returns rescued by the sale price is the exact signature of market-carried performance.
On your current deal, the underwriting assumption carrying the most weight is the $340 premium on $14k per door. Ask what premium their existing comparable properties are actually achieving today, in current rent rolls, not in a projection. If the answer is $240, the deal's equity return roughly halves and no amount of sponsor skill fixes it.
The risk you haven't raised is the debt. Bridge debt on a three year term against a business plan that needs full renovation and lease-up means the loan matures near the moment the property is fully stabilized, and refinancing has to work at whatever rates exist then. Ask what the extension options require, whether there's a rate cap and when it expires, who pays for the replacement cap, and what DSCR the lender tests. A sponsor who has never managed a maturity in a bad market has an untested skill precisely where it matters most. Ask them directly what happens if the property is at 88 percent occupancy at maturity and the refinance is short by $3M.