Both of these financing can be obtained as long as you have good credit. 

This is the biggest need in history for the wealthiest generation in history.

The seller doesn’t need to know that the underwriters may give you more of a hassle than other buyers.Or do you have lines of credit or a private lender so you can make a “cash” offer then try to get the financing through before close or at worst just do a cash out refi after close?

Unlike traditional banks, which focus heavily on personal credit and income, portfolio lenders prioritize the cash flow of your property.

We have credit scores over 730 and have been "soft approved" for around $750k. 

So do a background/credit check, get a full application, paystubs (Call to verify), former landlords phone #s (Call to verify), and other information.

., a duplex or multifamily), you may qualify for a conventional loan with as little as 3%-5% down.HELOC or Cash-Out Refinance: Use the equity you’ve built in your current property to secure a Home Equity Line of Credit (HELOC) or cash-out refinance.

Screening tenants well and then a security deposit or credit card hold process in place will limit liability.

Before you get too far, I would go talk to every local bank and credit union in the area you want to do this. 

In some cases they cannot pull the money out because it is now (Non-owner occupant) an investment and their credit union or bank may cap them at 70% or 75% MAX LTV.Nothing wrong wiht putting 10% down on a primary but look at the rates on both 5% and 10% usually when you have PMI built in the rates stay the same.