10-yr Interest Only ARM - Yes or No?

I'm looking to buy a home in Houston and am mulling over different options and would like the MB’s help:

I should set the scene by saying:
- I'm sitting on lots of cash
- I have always been very fiscally conservative.
- The probability that we’ll be in this house for > 10yrs is pretty low (< 10%)

I need to decide what to do with the cash and, depending on that, what to do about a mortgage.

After putting aside emergency funds and other such liquid safety nets, I’ll be able to put a minimum of 20% down, and may even be able to pay cash for the house depending on the price. Normally, I’d want to do this to avoid paying interest, but instead I’m leaning toward borrowing as much as possible and putting the cash to work in the market in relatively low-risk investments that I hope can return at least 4% annually. Generally, the expectation/hope is that I’ll be able to make more in other investment avenues than I’d be paying in interest on the mortgage.

It should be noted that Property Taxes in Houston are super high, so even if I have no mortgage, I’m still going to be shelling out 2-2.5% per year in Property Taxes, which is a strain on cash flow.

Question 1: Do I throw as much cash as possible at the house and minimize the amount I borrow, or borrow as much as possible at low rates and put the cash to work elsewhere?

Now, under the scenario that I borrow the maximum amount I can, I’m considering 2 options:
a. 30-yr Fixed Traditional Mortgage
b. 10-yr Interest Only ARM

Option a is my “base case” and is the only kind of mortgage I’ve ever gotten in the past, but if we buy a house that meets all our criteria in the area we need to be in, the payments for this combined with the property taxes are going to put some strain on my cash flow that I’m not sure I want. So I’m considering Option 2 to minimize payments. I recognize I won’t be building any equity in the house, but I’m not expecting significant appreciation in home values and don’t see the point in locking up my cash in home equity if I know I’m going to sell in less than 10 yrs. Also, I can always liquidate other investments to pay down the principal if I want or need to. Also, if we’re still in the house in yr 10, I’d expect to either refinance or just pay it off provided I haven’t totally lost my arse in other investments.

Honestly, Option B makes sense to me on paper, but I have this spidey-sense of fiscal conservativeness that’s telling me it’s a bad idea, but I can’t quite pinpoint why.

Question 2: Am I an idiot for considering Option b? What are the major risks and downsides that I’m missing?

Appreciate the guidance from the brilliant minds on the Money Board.