Also, one big downside to SFHs is that the occupancy can go from 100% to 0% with just one tenant, something I'm sure will concern lenders. 

I highly doubt a month to month tenant will throw $1000+ to repaint a place if I could for any reason kick him out on month #2.The financing aspect someone already discussed, many banks sees yearly lease as stable income and monthly leases as something less desirable.The downside of yearly or longer leases is you can't raise rent except at renewal time if the market goes up, and even then many landlords feel the obligation to keep rent the same for a good tenant. 

Is there a possible downside to not doing so?

I did that based on the advice of a friend that does evictions.There is ZERO downside..... if people want to leave, they leave regardless of the lease terms..... and that warm fuzzy feeling of a long term lease is an illusion... you are not likely to see a dime of the remaining lease if they bail.On the flip I can get rid of them WAY faster at any time I decide....

Lotta downside there I guess...

The downside (I prefer that term rather than “con”) is that there is a larger outflow of capital and time as the facility gets built, leased-up, & stabilized.

I personally find the biggest downside to be on CRM for lead management on listed rentals.

I'm looking at different options for opening a business checking account for this purpose.Are there any obvious downsides I may be missing in going with an online-only bank like BlueVine?

The only downside is places like Keller Williams and Exit Realty offer a lot of education and training in real estate sales.  

It looks like his main downside is that he's out time, but not out money unless he signs as a loan guarantor. 50/50 split isn't great either.