That's really interesting - so your payments are only fixed for 10 years (and at a lower amount, since it's interest-only)? I suppose you're betting that either:

- You'll sell the house before 10 years

- Rates will go down and you can refinance

I'm in a more standard 10/1 ARM for similar reasons - the interest rate was lower and I felt it was a reasonable bet that we'd be able to refinance for a better rate (or worst case slightly worse rate) in the next 10 years.