I then went a step further to send him the pro forma I put together that clearly states some of observations I've made that I don't think he is considering and included a personal message inside the pro forma, asking that he could pass it on for the seller to see... within a few minutes he responded with a short "No - Our Counter Stands."

Of course, with all things, the answers to all these matters will depend on the circumstances.California tends to have more laws on the books and requirements and restrictions that it can be a good idea to form a CA LLC for out of state property so that you as a CA resident are covered, and to try to have your contracts fall under the purview of CA courts.

@Anthony Harris, would you like to be the one to try out a seemingly untried strategy:- showing them realistic/conservative pro forma predictions (rather than best/optimistic ones)?...

My main caution at the moment is to get up-to-speed on NYS laws and be wary of purchasing occupied properties without verifiable pro forma. 

In Washington state we sometimes transfer in or out of an LLC and simply write "mere change of Identity" on the tax form. As

The "pro-forma trap" will bite you if it doesn't prove to be accurate. 

I'm debating whether to form a partnership agreement or if I should somehow put my name on deed?

Here are the numbers:Purchase Price: $419,900Monthly Income:$4,800.00Monthly Expenses:$3,609.91Monthly Cashflow:$1,190.09Pro Forma Cap Rate:7.32%NOI:$36,607.00Total Cash Needed:$57,371.00Cash on Cash ROI:24.89%Purchase Cap Rate:8.93%Total operating expenses:Mortgage expenses:Vacancy:$144.00Repairs:$144.00Water & Sewer:$200.00PMI:$285.00Insurance:$416.00P&I:$1,860.49Property Taxes:$460.42Misc:$100.00

What makes a good partner, or an unnecessary one to begin with.First, there are only three reasons to form a partnership, and each partner must fill one of them, or don't partner with that person/entity:1 - The Partner in question must do something you can't do (the obvious one),2 - The Partner in question must do something you don't want to do (if you don't want to do it, you won't do it well),...and the last one, but the most important one...3 - The Partner in question must do something you shouldn't do. 

If the pro-forma or actual cash-flow is satisfactory, I'd say go ahead and do it!