You can of course give them additional money if needed to achieve the sub-to. 

I know you know this, but you will need many more skills and subs than you present.

Of course, you could invest using cash only but then you might as well do that overseas and make significantly more money.Many are still pinning their hopes on the fact that they can buy today and refinance later at lower interest rates and hope that these rates go back to sub 3% again.

Just like everyone out their who are  Big company's like Walmart, Target, etc. have daily issues with customers that need to be resolved in person or online or complaints with the BBB. 

Obviously paying interest on underutilized capital is sub-optimal but when factoring in the cumulative proposed transactional savings, the annual total interest cost could be equivalent or lower than the net of an alternative home equity line of credit on the same principal loan amount.One 'hack' could be to delay the actual closing of the DSCR loan until a quality purchase prospect is identified and/or near under contract.

Have good customer service?

We meet monthly and have 3 sub-group meetings the rest of the month for our annual members.

Got the same, poor customer service.

that I think likely you can outdo Google customer service, haha.

They will look bad and it will likely cost them customers.