However, their terms involve a 20-year amortization, a 5-year ARM, and a rate of prime + 0.5% thereafter.I’m exploring other options for financing and would appreciate any suggestions or advice.

You may come across pushback with having co-gendered units so as you grow I would suggest leaving room to have unit(s) that are male and female only for those who are more comfortable with living with others from the same gender. 

I am afraid we will fall for a property with a false sense of a good deal.Are there any suggestions to help me run an analysis that would better account for the larger down payment and allow me to better analyze potential properties in the future.

DTI is generally only used for "Retail" or "Consumer" mortgages where you live in the property.So a conventional/DSCR "commercial" loan doesn't necessarily mean higher interest than a "consumer" mortgage if it's coming from a traditional bank/credit union? 

HI @Jacob KazmierskiI would suggest saving a certian % you fee comfortable with and then put the rest into a high yield savings account.

I would potnetially even suggest they pay a big more than value if they are getting that good of a payment/rate.

Any suggestions will be helpful.

Suggest you find on your own and have a licensed realtor to represent you. 

I stopped paying the 1%+ and my principal finally started to decrease, significantly.My suggestion is that you ask brokers for recommendations that are in the area where you are purchasing your property and keep calling banks and save thousands of dollars you can use to invest for your next purchase.Two things:  Your broker wasn't getting rich on a 1% commission and the 1% you paid to your broker didn't keep your principal from decreasing; it was probably the cash out he got you (and at a higher LTV than the bank would lend you I might add).Banks and brokers each have a place in the lending arena.Stephanie 

I'd suggest avoiding co-ops if you want the option to rent it out later.