Overall sale prices of homes are lower than most areas so that 100-200K can be multiple down payment on investment properties.

.- get into real estate with a lower rate and lesser percentage down payment.

.- My Resources / Constraints: I'm in a by no means unique, but perhaps less common situation for those getting started; I'm a somewhat senior software engineer at a tech megacorp and should be able to save a couple of down payments per year for lower priced houses (100-200 in my area), or perhaps one medium priced house (300-500).

If you are in a lower asset class things can go the other way. 

Sometimes too portfolios allow you to include lower valued properties that might not be eligible for regular DSCR lending. 

Quote from @Jaycee Greene: it all depends on the credit scores, but consumer mortgages tend to have lower interest rates than commercial loans.

Say, 3 month later, I decide to do a cash out refinance of the replacement property at 75% LTV because the rate is lower.

I still think this might work, but I will need to look at it from a few different angles.I like the idea of mobile homes because it's a lower cost way to get started.

Expanding to nearby areas with lower costs and strong rental demand can also make sense.

We focused on 1 and 2 br properties long before MTRs became trendy because they have lower price points, less competition, lower expenses, and while the tenant pool is smaller, so is supply.