I've found that Arizona, Texas and most mid-west states give both good cash flow for rentals and sufficient appreciation for fix & flips.

@Jimmy Solano, although you "really like / prefer the 14 unit property", I'm not convinced that "its lower asking price" is sufficient enough reason.

Or does $100 per door cash flow theoretically let you sleep at night?

If the savings did not seem sufficient, I might see if his parents could co-sign.

My goal is to pursue the BRRRR model as I want to generate sufficient income from multi-unit homes to allow me to expand my investing business into a full-time affair replacing my current 9 to 5.

I would lose sleep over it .Hope that helps a little.

That's my excuse for ready with my eyes and, sleeping with my brains...and the loan in question I got was a 403b.

However, while the results of your big lift may be lower operating and maintenance costs, if the local market will not support sufficiently high rents to provide a timely pay-back, you have over improved.   

Based off the numbers, I’m not going to lose any sleep over possible vacancies.

I hope that helps you sleep better at night!