I still haven't upgrade to the newest firmware on my Inspire 1. Should I stay where I am, or upgrade? What do you suggest?

If you are using the manual settings for choosing video feed frequency some might advice you to stay on an older firmware ... (I´m not one of those).
I am flying on the current firmware and I am having no issues ... although some concerns about the new firmware for the batteries ... but as that also solved other previous problems I still would do the update and as long as you start with fully and newly charged batteries you should be good.  

If you experience problems you cannot expect any support from DJI unless you are using the current firmware ...

Based on my experience from previous firmware and using the Inspire the way I do (flying in line of sight) ... I would update!

Good idea to save a copy of all updates so you can have the option of reinstalling if you Find it not what you expect