Rentals are more predictable and carry less risk.

I can't predict national markets; so, I invest to force appreciation and generate cash flow...and invest in properties and locations that are less susceptible to negative market swings.

Instead it is having tight systems and processes to produce a predictable outcome just doing the things they are supposed to.  

I'm not trying to be a "downer" but... all these optimistic predictions from people who financially benefit from optimistic conditions in the market are a bit misleading. 

I like this one.3) Highest risk because too much carrying costs with hard money, inability to predict where market will be when it's time to sell (9 months + modular construction time), opportunity cost if your funds are tied up and another deal comes along so I'm not a fan, negative cashflow like crazy over a long period of time is no bueno.Like the numbers on your deal, too bad 9 months + build time is really far out.

You can't predict future liquidity, lending standards, interest rates, etc.

then I'd predict that agent is not going to last long in this industry. 

You can not predict the future.

You can tell if you are going to need cosmetics from the pictures but system replacements will be harder to predict.

Another thing to keep in mind is if you need to refi to get money out in a couple years in the future for your next down payment there is a big possibility you will be doing so at a higher interest rate.If you pay more down you are not reducing what you are paying monthly just shortening the number of payments in 25-30 years.It looks to me you are in a growth stage and having a stable predictable property with more debt (paying off at a regular rate).