It is possible to create a FLEXIcontent category to replace the frontpage (com_frontpage).

Like this:

1. Create a category e.g. called "Frontpage Items".
2. Go the the (SYSTEM) FLEXIcontent advanced route plugin and select to exclude this category from routing (=meaning no links will be created to it, e.g. when displaying the categories of an item this category will not be listed)
3. Duplicate a template (e.g. the blog template and call it called "frontpageblog") and assign it to the category "Frontpage Items"
4. If needed, edit the files of this new template (particularly the category*.php files) to customize them.
5. Assign the items you wish to appear in the frontpage to this category.
   Of course the items will be assigned to both the "Frontpage Items" category and their normal category(-ies) (use CTRL-click to select)
6. Create a --new-- menu item that points to the category "Frontpage Items" and set it as --default-- so that it becomes your home page.

You are done !!