Does the fund fee make sense against doing it myself with $400k?

Your deployment drag is the biggest number in the post and you've left it out of both columns. If average capital deployed across the first 18 months is 55% of $400k, then a 12% statutory rate on deployed capital is under 7% on committed capital for that period, and that is before your $7,000 to $11,250 of servicing. Run the fund the same way, on committed capital, because that's what the 2% is charged on and probably what the preferred accrues against, though I'd read the actual language rather than the deck. Do it that way and the comparison stops being close in either direction until you know the sponsors' own deployment pace. Ask them what percentage of committed capital was placed at month 6 and month 12 in their last two vintages.

The comparison you're setting up depends on one assumption you haven't tested, which is whether the fund's realized rate resembles the statutory rate at all.

In a premium-bid county the certificate pays the statutory rate on the tax amount, and the premium you paid above that generally earns nothing, so a competitive sale converts a stated 12% into something materially lower on cash out the door. Ask each sponsor for realized yield on redeemed certificates by vintage, net of premium paid, rather than the statutory rate on the cover page. If they can only give you the statutory rate, that tells you something about the reporting you'd get for three years.

On the direct side, your servicing quote of $28 to $45 per certificate is a fixed cost, which means small certificates are structurally worse for you than large ones at identical rates. A $600 certificate at 12% earns $72 a year and eats half of that in servicing. Sort your three counties' historical sale files by certificate size and see whether $400k can even be placed in tickets large enough to carry the load, because that constraint may decide the question before fees do.

Most certificates redeem, so both routes are fixed-income exposure with an occasional property outcome attached. The property outcomes are lumpy and procedurally slow, and a fund reporting quarterly can look flat for a long time while a foreclosure runs.

Fund interests are usually securities, and whether a specific offering fits your situation is a question for your own counsel and accountant. Confirm the fee base, the preferred accrual base, and the extension language in the documents themselves rather than the deck.

The extension at their option is the clause I'd push on hardest. Three years plus one at the sponsor's discretion, on a strategy whose slow outcomes are foreclosures that take years, means you should assume four. Also ask what happens to a parcel the fund takes title to. Some of these vehicles are set up to buy paper and have no plan or budget for owning a house with a caved porch, and that's where the reporting gets vague.

Naive angle, but if the fee load and the servicing haircut land in the same place, isn't the deciding factor just whether you want 18 months of your own calendar taken up by sale dates? @ledger's point about average deployed capital would push me to the fund and @canton's point about the extension would push me back. I'd want to know what the direct route costs in hours before I called it a tie.