Remember even private money can be 6-10% and shorter term. 

Can be shorter or longer your choice.

My cash becomes available again monthly as I pay the principal down.I know most investors love to leverage and that my cash flow will be a little tighter because of the shorter amortization schedule, but I'm just trying to understand why I wouldn't do this?

As the days get longer the market slows, as it get's shorter it causes prices to goes up. 

But since there is a limit to how much money the bank has access to....their rate will be higher...and usually a shorter term.

I am doing a 5yr ARM 20yr AM as a commercial loan (LLCs allowed) for under 4 right now in my market of KY so they are out there for under 4 percent but on a shorter amortization.

Depending on if you itemize your taxes or not and if you can afford to be cashflow negative you may want to try for a shorter loan. 

One huge risk of being over-leveraged is when you have a mortgage with a term shorter than the amortization period (most all commercial mortgages). 

Hard money: “The Pros and Cons”Pro-All CASH Transaction-Quick Closing Times (<14days)-All “Rehab Cost” are covered in Loan-Lower Leverage for Buyer and more Liquidity-Flexibility to buy Distressed and Value-Add Properties-Loan based on Property and underwritten so Borrower is Profitable-Does not show up on Credit Report-No “DTI” (Debit to Income Ratio)CON-Higher interest rate than Bank-Shorter Repayment Schedule (<12 months)-More conservative evaluation of the Property’s Value-Not doing your research and working with a “Bait and Switch” Lender (check out our post on this)Real Estate is one of the most dependable and powerful ways to grow your wealth.

Trailers that occupied as a residential dwelling are considered permanent property by the IRS and are 27.5And land improvements or infrastructure driveways, landscape ect are shorter life and can potentially qualify for bonus depreciation.