Understanding the preferences of the Hamptons luxury market is essential.

Definitely call your preferred lender to ask though. 

Though he prefers to reposition existing multifamily properties, he has also subdivided land, built homes, and constructed self-storage.

Personally I’d prefer having all my loans with one entity like my local credit union who doesn’t sell them and just have the payments come out of my account that I already have with them, keeping it as simple as possible. 

I would prefer to have control over my own property.

HOLD & REFI - The improved cashflow (I have one lender saying he could get me into a DSCR loan at 6.5% which would 3x my cashflow) is enticing, but I'm don't want to risk anything especially having been burned once and would prefer to be on the up and up. 

I was unfortunately denied as of yesterday, but she said it's because I am a new customer for Key.

Customer service is always great when they have something to sell, I am sure you know this. 

It will depend on your preferences and how well you think you will tolerate having a room mate as you approach a new life with your partner.

Engage an investor-focused realtor/broker in your preferred market (this is not a residential realtor) and start 'tire kicking' the market and properties that fit your criteria.