WMF 5.1 has been added to Windows 10 build 14342 and can be installed using the fast ring.
Note: If you’ve been relying on a wildcard to load all of your exported functions you may run into issues.
See, using wildcards cause up to 15 seconds of lag when loading the module. The new Update-ModuleManifest now explicitly creates an empty collection if you don’t provide input to the corresponding parameter. Make sure to explicitly state which functions, variables, and cmdlets.