Well, the major change took place when Aware went from Sencha UI to Kendo UI, which was from V6 to V7. Although aware team did an exceptional job to ease the pain, but you need (to be on safe side) to go through every form and query and adjust the UI. Not sure you have developed Mobile in 5.9, which now is a lot different.
That's the bulk of your work. And this change will bring you to V7 and since you're using V8 editor, then while you are in each form, query and VP, make all the changes to suit V8 as well.
It will be a long process, don't rush it.
