During this era the 914 used the same geometry as the higher end models. The differences on these models were higher end compoents and/or more exotic frame materials such as titanium or carbon fiber.
As for curb hopping it's no problem, provided you do it right and land light. However, one mis-judgement and you have a pretzeled wheel, bent frame or worse. To me, the MTB or Jamis would be more approapriate for the commute. However, should you continue to commute with the Miyata, post a pic before the scars get too bad.