I've been going through the same conversion process, and cannot yet switch to Mx5 because not all features from v4 can yet be replicated in v5. However, many of the uses of the formloader widget still work or can be replaced with use of a snippet in Mx5.
Using a formloader in a template grid still seems to work. Using a formloader in a Shared Node ID, to place it in a page header area for instance, does not work. You may be able to replace this with a snippet placed in your layout template instead.
Added: When I try to replace a formloader element with a snippet in a template grid, the new snippet is read-only, so cannot replicate the functionality of the formloader properly.
if someone cares about formloader for Mx5.11. Here it is https://dl.dropboxusercontent.com/u/2062352/other/FormLoader.mpk
Sorry to revert to my previous post, Just found out that i (expirimental) fixed this widget 2 months ago..... but i forgot. Would have shared with you if the app store is more community driven. like requested in: https://forum.mendix.com/questions/5984/Post-All-your-Widgets-on-GitHub
Flock of Birds developed a version fox Mx5, If Mendix permits I post it to GitHub too. https://www.dropbox.com/s/dht3kjr5ol9jjy0/FormLoader.mpk
Eh, I thought snippets are meant to replace the formloader features, am I right? See this.