You shouldn't lose anything, I know some players transferred over to Steam some time back with no problem. What you do is "Link" the Emporea account to the Steam account.
We have been looking at this in our group for a little while. One of our members posted this photo and comment:
"I got my code from pixel, in settings>link>this is my old account, generate button"
I will be creating a Steam account next month and will post step-by-step instructions.
If you have problems, contact Support.