An appraisal 30k light on a duplex refi, and whether to take 75% now or season six more months

I'd take the 65%. You are describing 22k of proceeds that cost you a higher rate, a bigger payment for thirty years, and a point to the private lender if you wait. What is the 22k actually going to buy in the next four months? If the answer is nothing specific, it is not proceeds, it is just debt you took early. I hold things for a long time and the payment I signed at the start is the thing I live with, so I bias toward the smaller one.

The answer turns on whether 245k is a comps problem or a rent problem, because those have different fixes and only one of them is worth waiting for.

If the shortfall is comp selection, a rebuttal with closer, better matched duplex sales is the cheap path, and it does not cost you a point to the private lender. If the shortfall is that your market genuinely has thin small multifamily sales volume, six more months may not produce the comps you need, and you will have paid extension fees plus 10.5% carry for the privilege of finding that out. Ask the appraiser's reviewer which sales they would consider, in writing, before you decide to wait.

On the marginal cost of the last chunk of proceeds: going from 65% to 75% of 245k adds about 24.5k of debt. If that step also moves your rate, the effective cost of that 24.5k is well above the headline rate, because the pricing bump applies to the whole balance. Get both quotes priced on the same day and compute the payment difference, then divide it by 24.5k. That number is what the money actually costs you. Lender cash-out limits on 2 to 4 unit properties and any seasoning requirement vary by lender and by program, so confirm both in writing rather than working from what was true last year.

Also worth pricing separately: 22k of trapped equity is only a problem if you have a use for it that beats the rental's own return. If your next acquisition is nine months out, the case for taking the maximum today is weak.

One correction to your framing. Your DSCR of 1.33 is computed on gross rent. Most lenders will use gross rent for the ratio, and your own underwriting should not, since vacancy and capital reserves come out of the same 2,300.