I do not have any loans through Flagstar Bank, but I would talk to them prior to moving it into the LLC.

If you pay down $100K in loan saving you $1K in monthly costs against rental income, or you invest that $100K in something that generates $1K in net income the result is similar.

To achieve this, I’m planning to scale rapidly by performing a couple of syndications to acquire a larger portfolio.I currently have a portfolio of 17 properties, but to justify labor costs and create a sustainable structure, I need to expand quickly.

In addition to conventional loans and FHA loans, if either you or your wife are veterans, the VA also has a rehab program.I'd be happy to discuss my rehab experience both as an investor and as a mortgage broker, and at least help you think through your options. 

@Jake Baker  You should think about a rehab loan if you are going to buy and hold.

I've tried the lower 6-7% PMs and usually you'll either pay mark ups on repairs (what you've noted) or pay extra fees (i.e. labor hours, extra calls) that you may or may not notice. 

Are you using the 10% down second home occupancy loan?

you can use a DSCR loan if your DTI is too high for conventional. 

Another pro for a HELOC is not having to meet a HML's requirements for a loan (insurance, draw schedules etc....)

If so what are his loan requirements?