ARMs aren't always right for everyone. But I think there's been a lot of (deserved?) negative backlash to ARMs based on people's experience from '05-'09 with I/O ARMs and the underwriting process that went into selling those products. Those products are no longer available, and underwriting is as strict as its ever been. So if you think you might move in the next 7 years, and the money you save on a ARM vs. 15 or 30-year fixed rate would let you max out a 401k or Roth IRA, then it might be worth it.

If you're just going to use the money to increase your lifestyle, then probably not. But I do think you should consider it if it helps you meet other goals. Otherwise, you're paying a premium for a fixed rate on a term that you'll never even use.