What are the differences...  reasons to upgrade from the gimbal/camera I received with my Inspire 1 that I bought a year ago?

Also - Does anyone know what the warranty period is from DJI on the gimbal?

An advance - thank you!

I am sorry I am trying to understand what you are trying to say.

Are you trying to compare your X3 with the new X5 camera?

The gimbal I believe is 1 year from the purchase date.

Well, there is a pretty huge difference between X3 and X5 cameras, you can check it here:  
http://www.dji.com/products/compare-xcamera