You are not paying for their services and won't cost you anything extra anyways. 

If you can come up with an extra 1.5% and finance with a conventional loan you have none of those downsides, a lower monthly payment and PMI only until you hit 20% equity

This would obviously reduce my cash flow on both properties, as I would be paying the minimum HELOC payment plus extra towards the principal to pay it off quickly.

I think the big question is how badly do you want to keep the extra $50k liquid?

I was drawn to the accessibility of their projects without needing to be a FUND, along with the extra benefits that come from their large-scale output.As an investor, my priorities are finding good deals, investing in landlord-friendly markets, and transitioning to new construction properties.

Since the properties are in New York you have a few extra steps you need to do to keep all of your funds out of NYs hands at closing.Here's an interesting BP thread on the South Carolina property tax issue you mentioned. https://www.biggerpockets.com/forums/725/topics/604427-south.... 

Now we have to build how many millions extra?

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Especially as you two plan to start your lives together, you’ll likely want that extra privacy.

The reality is the opposite - if it's not in writing then the PMC doesn't have to provide the service or can charge extra for it!